Methods for detecting and reversing resistance to macrocyclic lactone compounds

ABSTRACT

This invention describes novel purified and isolated nucleic acid molecules or the fragments thereof, extracted from nematode or arthropod pests or recombinant, which encode P-glycoprotein homologs and regulate resistance to the macrocyclic lactone compounds. The invention further relates to the new P-glycoprotein homolog expression product of these nucleic acids. Also described herein are methods for detecting the gene encoding for resistance to the macrocyclic lactone compounds in nematode or arthropod pests which comprise comparing the nucleic acids extracted from a pest specimen to the nucleic acids encoding for resistance and the nucleic acids encoding for susceptibility to the macrocyclic lactone compounds. Lastly, the present invention is also drawn to methods and compositions for increasing the efficacy of the macrocyclic lactone compounds against resistant nematode or resistant arthropod pests which comprise administering to a mammal or applying to crops and the like a pesticidal enhancing effective amount of a multidrug resistance reversing agent.

RELATED U.S. APPLICATION DATA

This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 60/045,160, filed Apr. 30, 1997.

FIELD OF THE INVENTION

This invention relates generally to novel methods for diagnosing and overcoming resistance to the macrocyclic lactone compounds. More specifically, the invention pertains to unique methods for detecting the development of resistance to macrocyclic lactones using nucleic acid probes and enhancing the efficacy of the macrocyclic lactones using multidrug resistant reversing agents.

DESCRIPTION OF RELATED ART

Macrocyclic lactone compounds such as the LL-F28249 compounds, the milbemycins and the avermectins are widely used for treatment of nematode and arthropod parasites. The highly active LL-F28249 family of compounds are natural endectocidal agents isolated from the fermentation broth of Streptomyces cyaneogriseus subsp. noncyanogenus. U.S. Pat. No. 5,106,994 and its continuation U.S. Pat. No. 5,169,956 describe the preparation of the major and minor components, LL-F28249α-λ. The LL-F28249 family of compounds further includes, but is not: limited to, the semisynthetic 23-oxo derivatives and 23-imino derivatives of LL-F28249α-λ which are shown in U.S. Pat. No. 4,916,154. Moxidectin, chemically known as 23-(O-methyloxime)-LL-F28249α, is a particularly potent 23-imino derivative. Other examples of LL-F28249 derivatives include, but are not limited to, 23-(O-methyloxime)-5-(phenoxyacetoxy)-LL-F28249α, 23-(semicarbazone)-LL-F28249α and 23-(thiosemicar-bazone)-LL-F28249α.

The milbemycins, also known as the B-41 series of antibiotics, are naturally occurring macrocyclic lactones isolated from the microorganism, Streptomyces hygroscopicus subsp. aureolacrimosus. U.S. Pat. No. 3,950,360 shows the preparation of the macrolide antibiotics milbemycin_(α1-α10), milbemycin_(β1-β3) etc. These compounds are also commonly referred to as milbemycin A, milbemycin B, milbemycin D and the like, or antibiotic B-41A1, antibiotic B-41A3, etc.

The avermectins, also known as the C-076 family of compounds, are naturally occurring macrocyclic lactones produced by the soil actinomycete microorganism, Streptomyces avermitilis. U.S. Pat. No. 4,310,519 discloses the isolation and preparation of the major components A_(1a) (e.g., avermectin A_(1a)), A_(2a), B_(1a) and B_(2a), and the minor components A_(1b) (e.g., avermectin A_(1b)), A_(2b), B_(1b) and B_(2b). The C-076 family additionally embraces the semisynthetic derivatives such as the 22,23-dihydroavermectins described in U.S. Pat. No. 4,199,569. The semisynthetic derivatives include, but are not limited to, ivermectin, abamectin, doramectin, eprinomectin and the like.

Resistance to all of the broad spectrum macrocyclic lactone compounds has been encountered in most regions of the world where the compounds are used routinely in animal production. For instance, drug resistance to ivermectin (IVM), chemically known as 22,23-dihydroavermectin B₁ or 22,23-dihydro C-076 B₁ and a commonly used member of the avermectin drug family, has become a widespread problem, particularly in nematodes of sheep, goats and cattle (Shoop, Parasitol. Today 9: 154-159, 1993). In some parts of the world, the survival of commercial animal production is threatened by the development of anthelmintic resistance. Additionally, there is conflicting evidence as to whether ivermectin (avermectin) resistance confers resistance to the related milbemycins or other macrolides (Arena et al., J. Parasitol. 81: 286-294, 1995; Oosthuizen and Erasmus, J. So. African Vet. Assoc. 64: 9-12, 1993; Pomroy and Whelan, Vet. Rec. 132: 416, 1993; Shoop, 1993; Condora et al., Vet. Rec. 132: 651-652, 1993; Pomroy et al., N.Z. Vet. J. 40: 76, 1992; Pankavich et al., Vet. Rec. 130: 241-242, 1992; Craig et al., Vet. Parasitol. 41: 329-333, 1992). The mechanisms of resistance to the avermectins, the milbemycins and other macrocyclic lactone compounds remain unknown.

P-glycoproteins (Pgp) were identified some years ago as proteins involved in multidrug resistance (MDR) of mammalian tumor cells (Julino and Ling, 1976; Gros and Buschman, 1993; Gotteesman and Pastan, 1993). MDR proteins may also be involved in drug resistance in the protozoal parasites Entamoeba histolytica (Whirth, Archivos De Investigacion Medica 21(Supp. 1): 183-189, 1990; Samuelson et al., Mol. Biochem. Parasitol. 38; 281-290, 1990), Leishmania enriietti (Chow, Mol. Biochem. Parasitol. 60: 195-208, 1993), L. dononani (Callahan et al., Mol. Biochem. Parasitol. 68: 145-149, 1994); and Plasmodium falciparum (Volkman et al., Mol. Biochem. Parasitol. 57: 203-211, 1993; Cowman et al., J. Cell Biol. 113: 1033-1042, 1991). While many researchers believe that the proposed mechanism for Pgp involvement in drug resistance is that Pgp behaves as a pump to increase drug efflux, Callahan et al. (1994) suggested that Pgp may work by decreasing drug influx. However, the whole picture of how Pgp can be responsible for drug resistance is still unclear.

Only recently have Pgp homologs been investigated in nematodes (Sangster, Parasitol. Today 10: 319-322, 1994; Lincke et al., EMBO J. 12: 1615-1620, 1993; Lincke et al., J. Mol. Biol. 228: 701-711, 1992). Three full length Pgp genes and one partial Pgp gene from the free-living nematode, Caenorhabditis elegans have been cloned, sequenced and mapped to chromosomes I, IV and X (Lincke et al., 1992). Sangster et al., J. Cell Biochem. 17 (Supp.): 1223, 1993, indicated evidence for several partial genes for Pgp in the parasitic nematode Haemonchus contortus, although sequence information was missing. In vivo experiments have shown that disruption of the mouse mdr1, a P-glycoprotein gene, leads to an impairment in the blood-brain barrier and to increased sensitivity to drugs in these mice (Schinkel et al., Cell77: 491-502, 1994). Mice with deletion of mdr1a were 50-100 times more sensitive to ivermectin than normal mice.

Drug resistance based on overexpression of P-glycoprotein has been shown to be reversed by verapamil and a number of other calcium channel blockers, calmodulin antagonists, steroids and hormonal analogs, cyclosporins, dipyridamole and other MDR-reversing agents (Ford, Hematol. Oncol. Clin. North Am. 9: 337-361, 1995). However, there has been no report or suggestion in the literature to use MDR-reversing agents to combat resistance in nematodes and arthropods to pesticides.

There is a definite need to understand the mechanism of macrocyclic lactone resistance, to be able to detect insipient resistance before it becomes flagrant and is difficult to manage the health of the animals. The ability to reverse the resistance has great potential for maintaining parasite control in the face of a failure of conventional treatment. An important object of the present invention, thus, is to determine these mechanisms of resistance in order to find viable, sensitive means to detect and to overcome the problematic resistance thereby improving parasite control.

BRIEF SUMMARY OF THE INVENTION

Heretofore unknown, it is now found that the mechanism of resistance to the macrocyclic lactone compounds is due to overexpression of novel P-glycoprotein homologs. It is further newly found that the nucleic acid molecules encoding the P-glycoprotein homologs or the fragments thereof regulating this resistance are useful as unique probes in methods for diagnosing the resistance to the macrocyclic lactones. For the first time, the reversal of resistance to the macrocyclic lactone compounds using multidrug resistance reversing agents is described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The background of the invention and its departure from the art will be further described hereinbelow with reference to the accompanying drawings, wherein:

FIG. 1 shows the 432 bp PCR product which is generated from a Haemonchus contortus cDNA pBLUESCRIPT® library as template and degenerate primers based on the conserved ATP binding domains of Caenorhabditis elegans P-glycoprotein genes after electrophoresis on an agarose gel.

FIGS. 2A and 2B represent, respectively, the nucleotide sequence of the 432 bp PCR product shown in FIG. 1 and the predicted amino acid translation of the cDNA (which correspond to SEQ ID NO:1 and SEQ ID NO:2, respectively).

FIG. 3 shows the autoradiographs of the Northern blots of RNA extracted from eggs of ivermectin sensitive and resistant (MKIS and MKIR; ACIS and ACIR) nematode strains respectively. The [³²P]-432 bp PCR product, with homology to Pgp, is used as one probe and a [³²P]-actin fragment from pBA1 is used as a second probe.

FIGS. 4A to 4B represent the full-length cDNA sequence (4175 bp) of the PGP-A clone from the H. contortus cDNA library with high homology to known P-glycoproteins (which corresponds to SEQ ID NO:3).

FIG. 5 represents the partial cDNA sequence (1810 bp) of the 5′ end of the PGP-A clone from the H. contortus cDNA library (which corresponds to SEQ ID NO:4).

FIG. 6 represents the partial cDNA sequence (2698 bp) of the 3′ end of the PGP-A clone from the H. contortus cDNA library (which corresponds to SEQ ID NO:5).

FIG. 7 represents the putative amino acid translation (1275 a.a.) of PGP-A cDNA (which corresponds to SEQ ID NO:6).

FIGS. 8A to 8B represent the partial cDNA sequence (3512 bp) of the 3′ end of the related but different PGP-O clone from the H. contortus cDNA library (which corresponds to SEQ ID NO:7).

FIG. 9 represents the partial cDNA sequence (2681 bp) of 3′ end of the related but different PGP-B clone from the H. contortus cDNA library (which corresponds to SEQ ID NO:8).

FIG. 10 shows the autoradiographs of the Southern blots of genomic DNA extracted from eggs of ivermectin sensitive and resistant strains of H. contortus (MKIS AND MKIR) after digestion with PvuII, electrophoresis and probed with the [³²P]-432 bp H. contortus Pgp probe.

FIG. 11 shows the restriction length polymorphism of PCR products from the DNA of individual male adult worms from ivermectin susceptible (lanes 1-9) or resistant (lanes 11-20) H. contortus strains, generated with P-glycoprotein primers PGP2S and PGPAS followed by digestion with DdeI and separation on non-denaturing polyacrylamide gel electrophoresis. The arrows point to the three digestion fragments that are associated with resistance.

FIGS. 12A and 12B represent the nucleic acid sequences comprising sense primer PGP2S (FIG. 12A, which corresponds to SEQ ID NO:9) and antisense primer PGPAS (FIG. 12B, which corresponds to SEQ ID NO:10) which are constructed from the nematode P-glycoprotein homolog cDNA clone PGP-O-3′ (53 bp intron region) and are used to generate PCR products that are diagnostic for macrocyclic lactone endectocide resistance.

FIGS. 13A and 13B illustrate the efficacy of moxidectin (MOX) against H. contortus susceptible (FIG. 13A) or moxidectin-resistant (FIG. 13B) strains in jirds.

FIGS. 14A and 14B illustrate the efficacy of ivermectin (IVM) against H. contortus susceptible (FIG. 14A) and moxidectin-resistant (FIG. 14B) strains in jirds.

FIGS. 15A and 15B illustrate the efficacy of verapamil (VRP) with or without ivermectin (IVM; LD₅₀) against H. contortus susceptible (FIG. 15A) or moxidectin-resistant (FIG. 15B) strains in jirds.

FIGS. 16A and 16B illustrate the efficacy of the combination of moxidectin (MOX; FIG. 16A) or ivermectin (IVM; FIG. 16B) with verapamil (VRP) against H. contortus moxidectin-resistant strain in jirds.

FIGS. 17A, 17B and 17C illustrate, respectively, the HinfI digestion of P-glycoprotein PCR fragments from the DNA of of individual worms of susceptible, ivermectin-resistant and moxidectin-resistant H. contortus, using primers PGP2S and PGPAS, followed by digestion and separation on non-denaturing polyacrylamide gel electrophoresis. The arrows on the right side of FIGS. 17B and 17C point to the digestion fragments that are associated with resistance while the arrows on the left side point to the position and size of the standard markers.

FIGS. 18A, 18B and 18C illustrate, respectively, the AluI digestion of P-glycoprotein PCR fragments from the DNA of individual worms of susceptible, ivermectin-resistant and moxidectin-resistant H. contortus, using primers PGP2S and PGPAS, followed by digestion and separation on non-denaturing polyacrylamide gel electrophoresis. The arrows on the right side of FIGS. 18B and 18C point to the digestion fragments that are associated with resistance while the arrows on the left side point to the position and size of the standard markers.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, there are provided novel purified and isolated nucleic acid molecules encoding new P-glycoprotein homologs or the fragments thereof which regulate the macrocyclic lactone resistance. These nucleic acids find use as probes in innovative methods for the early diagnosis of a developing resistance to the endectocides. In the past, there have been no DNA or RNA based methods of detection of macrocyclic lactone resistance available. Now, the present invention uniquely provides the genetic basis of the resistance and the diagnosis of resistance using nucleic acid probes. The early detection under the guidance of this invention allows for maintaining adequate control of parasites and maintaining the usefulness of the macrocyclic lactone compounds. Additionally, the mechanism of resistance to macrocyclic lactones can be used in development of screens for identifying new antiparasitic agents.

The novel methods of the present invention which are useful for detecting the resistance to macrocyclic lactone compounds in nematodes or arthropod pests utilize the new nucleic acid probes described herein. A variety of techniques well-known to those versed in the art can be employed for the analysis. Desirably, the method detects changes in genomic DNA or mRNA to provide a viable means for diagnosis of macrocyclic lactone resistance.

These methods include, for example, Polymerase Chain Reaction (PCR), hybridization in a Southern blot, Dot blot or Northern blot analysis or the use of an antibody to a sequence of peptides corresponding to the translation of the nucleotide sequences between the novel primers of the invention of an individual pest or mixture of the pests such as worms, using primers or probes, for example, corresponding to the portion of the cDNA sequence of PGP-O between the sequences identified as PGP2S and PGPAS (see FIGS. 12A and 12B). Alternative primers or probes within this region which can be utilized in the methods of the invention include, but are not limited to, all combinations of PCR primers or probes within this region or that of other PGP homolog sequences such as PGP-A, PGP-B, PGP-O and the like. Basically, the coding region of the P-glycoprotein homolog genes corresponding to the cDNA sequences identified as PGP-A, PGP-A-3′, PGP-B, PGP-B-3′, PGP-O, PGP-O-3′ and the like is detected by PCR, Southern blot, Dot blot, Northern blot, Restriction Fragment Length Polymorphism (RFLP) and other standard means of analysis. Surprisingly, it has been found that the digestion pattern from the PCR fragment, the blot data or the antibody-antigen reaction are associated with susceptible or resistant traits which are diagnostic for the development of macrocyclic lactone resistance.

Polymerase Chain Reaction (PCR) can be employed for the detection of resistance to the macrocyclic lactone compounds by synthesizing a nucleic acid product which can be probed in conjunction with the Southern blot analysis or initially digested with a restriction enzyme for RFLP analysis as described herein. The primers are used to initiate a PCR reaction using the nucleic acids extracted from the pest specimen. They are used to synthesize a P-glycoprotein sequence or sequences. The PCR products can then be cut with restriction enzymes and the digested sequences run on an electrophoresis gel. Examples of suitable restriction enzymes that can be employed in the digestion of the PCR products include, but are not limited to, AluI, DdeI, HinfI, RsaI and the like. The pattern of bands observed on a Southern blot or a Northern blot indicates which P-glycoprotein alleles are present in a pest specimen such as the worm or group of worms. Some of the alleles can be associated with macrocyclic lactonie sensitivity and others with resistance to macrocyclic lactones. The PCR products, followed by restriction enzyme digests, provide viable means for the detection of resistance. The process of cutting the PCR products or the nucleic acids such as DNA for the RFLP analysis greatly increases the sensitivity and specificity of the diagnosis.

Reverse Transcriptase—Polymerase Chain Reaction analysis (RT-PCR) can similarly be employed for the detection of resistance to the macrocyclic lactone compounds in nematode or arthropod pests. Typically, RNA from a nematode or arthropod specimen is extracted and reverse transcriptase followed by PCR, as described herein, is used to detect resistance.

By way of illustration, the nucleic acids, typically DNA for the PCR procedure or mRNA for RT-PCR, are extracted from the pest specimen, a pest known to be resistant to the macrocyclic lactone compounds and a pest known to be susceptible to the macrocyclic lactones. The nucleic acids derived from the resistant and the susceptible pests are used as a point of reference. The DNA, or cDNA produced by mRNA by Reverse Transcriptase, is denatured and the primers of the invention are added to form a mixture. The three mixtures are subjected to many cycles of PCR, usually digested by a restriction enzyme and subjected to gel electrophoresis. Subsequently, the pattern and the intensity of the bands from the specimen to that of the reference nucleic acids, i.e., DNA or cDNA, of the resistant and susceptible extracts are compared to detect the resistant population. optionally, hybridization by a probe of the invention or use of a dye such as ethidium bromide to assist in visualizing the bands is included in the process.

Novel probes are used in the diagnosis of macrocyclic lactone resistance by detecting susceptibility or resistance to the macrocyclic lactones in the PCR assay. The primers which are used in the PCR assay are constructed, for example, from the nucleic acid sequences for the parasite P-glycoprotein homolog cDNA clones. Examples of suitable PCR primers that can be employed in the PCR analysis are the primers PGP2S and PGPAS used in the sense and antisense directions, respectively, which are constructed from PGP-O-3′ or PGP-O (see FIGS. 12A and 12B). The primers can also be prepared from the full or partial sequences of other P-glycoprotein nucleic acids such as PGP-A, PGP-A-3′, PGP-B-3′, PGP-O, etc. and the complementary strands thereof which contain the region found to be diagnostic of macrocyclic lactone resistance. Alternative useful sequences can be obtained by conventional means such as hybridization techniques under standard or stringent conditions.

Southern blot, Dot blot or Northern blot may be prepared with the nucleic acid molecules from the nematode or the arthropod specimen and, using a probe comprising one of the nucleic acid molecule sequences encoding for resistance or portion thereof, one can compare the level of the nucleic acids extracted from the specimen to the level of the nucleic acids from the probe, for example, by measuring or detecting the level of DNA or mRNA . Generally, three nucleic acid extracts are mapped to make the comparison: from the pest specimen, from a pest known to be resistant and from a pest known to be susceptible. In the case of the Southern blot, the pattern of the bands is compared. With the Northern blot, either the pattern or the intensity of the bands is compared. For the Dot blot, the intensity of the spots is compared.

Another technique involves conducting a Restriction Fragment Length Polymorphism analysis (RFLP) by extracting the nucleic acids from a nematode or arthropod specimen, digesting the nucleic acid with a restriction enzyme, using a probe comprising one of the nucleic acid molecule sequences encoding for resistance or portion thereof and comparing the digestion pattern to that of the digestion pattern of nematodes or arthropods known to be from populations either resistant or sensitive to the macrocyclic lactone endectocides. When DNA is cut with the restriction enzyme, run on a gel and probed under the RFLP technique, the probe hybridizes with the similar sequences, but their length will vary depending upon where the restriction sites for that enzyme occurs. By repeating the analysis with DNA from individual worms, slightly different patterns are observed due to polymorphism. Specific patterns are diagnostic for the resistance gene. PvuII is an example of a preferred restriction enzyme that can be employed for RFLP analysis. Other conventional restriction enzymes known to those of ordinary skill in the art may be substituted in the method.

A further example of a process useful in the present invention for detecting resistance concerns making antibodies which employ the novel PGP protein homologs. For instance, an antibody may be prepared to a sequence of the peptide corresponding to the amino acid translation of the nucle ic acids or the fragment thereof encoding the P-glycoprote in homologs which regulate resistance. Then, a specimen of the nematode or the arthropod pest, or the extract thereof, is prepared for reaction with the above antibody. The specimen or the extract is reacted with the antibody under suitable conditions that allow antibody-antigen binding to occur and, thereafter, the presence of the antibody-antigen binding is detected by conventional methods.

The above-described methods for the detection of resistance to the macrocyclic lactone compounds can optionally use a P-glycoprotein specific ligand or dye. Usually, the level of the P-glycoprotein in the specimen can more easily be observed using the ligand or dye and compared to the levels obtained in known macrocyclic lacrone resistant and susceptible populations of nematodes or arthropods. The ligand or dye is usually radiolabelled so that it can be readily detected. Examples of suitable ligands useful in this method include, but are not limited to, prazosin, azidoprazosin, iodoaryl-azidoprazosin and the like. A variety of conventional dyes may be employed such as, for instance, rhodamine 123, ethidium bromide and others.

For purposes of this invention, the nucleic acid molecule may be DNA, cDNA or RNA. However, in the most preferred embodiment of this invention, the nucleic acid probe is a cDNA molecule. Many of the foregoing methods illustrate extracted nucleic acids from Haemonchus contortus. It is contemplated that the present invention embraces the use of recombinant nucleic acids encoding for resistance or susceptibility to the macrolides as well as isolated nucleic acids from other worm strains or pest species.

The plasmids containing cDNA derived from Haemonchus contortus are deposited in connection with the present patent application and maintained pursuant to the Budapest Treaty in the American Type Culture Collection (ATCC), 10801 University Boulevard, Manassas, Va. 20110-2209, U.S.A. The cDNA sequences described herein are contained within plasmids (pBLUESCRIP® II, commercially available from Stratagene Inc., La Jolla, Calif.) transformed into XLI-blue Escherichia coli bacterial strains. The plasmids identified as PGP-B-3′, PGP-O-3′ and PGP-A-5′ have been deposited in the ATCC on Jan. 29, 1997 and have been assigned ATCC Designation Numbers 98307, 98309 and 98310, respectively. The plasmid PGP-A-3′ has been deposited in the ATCC on Feb. 26, 1997 and has been assigned ATCC Designation Number 98336. It should be appreciated that other plasmids, which may be readily constructed using site-directed mutagenesis and the techniques described herein, are also encompassed within the scope of the present invention.

The present invention further relates to the unique reversal of resistance in parasites to the macrocyclic lactone compounds by administering or applying multidrug resistance reversing agents. This reversal of an existing resistance problem permits regaining satisfactory parasite control. The nematode or arthropod parasites or pests of this invention refer to crop insects, crop or mammalian nematodes, arthropod ectoparasites and endoparasites of mammals including acarids and the like.

Desirably, the multidrug resistance reversing agent is a calcium channel blocker such as verapamil, nifedipine and the like; a calmodulin antagonist such as trifluoperazine, prochlorperazine and the like; a vinca alkaloid analog such as vindoline, thaliblastine and the like; a steroidal agent such as progesterone and the like; a hormonal agent such as tamoxifen, estradiol and the like; an immunosuppressive agent such as cyclosporin A, SDZ-PSC 833 and the like, an antibiotic such as erythromycin, cefoperazone, ceftriaxone, tetracycline and the like; miscellaneous compounds such as dipyridamole, quinidine, reserpine, amiodarone, etc.; and other multidrug resistance reversing agents known to those versed in the art.

To increase the efficacy of the parasiticidal macrolides, the compounds of the invention are administered to mammals orally, parenterally, topically (local activity) or transdermally (systemic activity) depending upon the bioavailability of the selected medicinal by the desired route of administration. Parenteral administration of the medicinals encompasses any means other than orally, such as, for example, intravenously, intramuscularly, subcutaneously, intratracheally, intraruminally, etc. It is apparent that the MDR-reversing agents are administered in connection with the administration of the macrocyclic lactone compound encountering resistance in the nematodes or the arthropod ectoparasites or endoparasites of mammals. However, the administration of the MDR-reversing agents may be made either before or during concurrent administration of the macrocyclic lactones. If the MDR-reversing agent will be given before the endectocide, medical or veterinary personnel can readily determine by appropriate blood levels how far in advance the MDR-reversing agent may be given for increasing the macrolide's efficacy. Typically, the MDR-reversing agent will be administered within 24 hours of the start of endectocidal therapy and, preferably, within 4 hours before or concomitantly with administering the macrocyclic lactone.

In terms of dosage, the suitable amount of the MDR-reversing agent which is effective to increase the efficacy of the macrocyclic lactone compound against resistant nematodes or resistant arthropod ectoparasites or endoparasites will typically vary within a wide range of amounts at a variety of concentrations. The particular MDR-reversing agent selected for use with the specific endectocide will clearly affect the useful dose of the MDR-reversing agent. It is contemplated that selection of appropriate dosages of each MDR-reversing agent and the macrocyclic lactone compound to achieve the pesticidal enhancing effective amount can be easily titrated by routine testing known to those having ordinary skill in the medical and veterinary arts.

For use in parasiticidal treatment, the macrocyclic lactone compounds may be administered orally in a unit dosage form such as a capsule, a bolus or a tablet. The capsules and boluses comprise the active ingredient admixed with a conventional carrier vehicle such as starch, talc, magnesium stearate or dicalcium phosphate. The dry, solid unit dosage form are prepared by intimately and uniformly mixing the active ingredient with suitable finely divided diluents, fillers, disintegrating agents and/or binders such as starch, lactose, talc, magnesium stearate, vegetable gums and the like. Such unit dosage formulations may be widely varied with respect to their total weight and content of the active agent depending upon factors such as the type and the weight of the mammal to be treated and the type and severity of the infection or infestation. Generally, the amount of the macrocyclic compound given in oral administration is about 0.001 mg to about 10 mg per kg of body weight and preferably, about 1 mg to about 5 mg per kg of body weight. However, the amount will vary depending upon the extent of the resistance already developed in the parasite.

For animals, the macrocyclic lactone compound and many of the MDR-reversing agents can also be administered via ar animal feedstuff by intimately dispersing the active ingredient in the feed or using as a top dressing or in the form of pellets which may then be added to the finished feed or optionally fed separately. Suitable compositions include feed premixes or supplements in which the active compound is present in relatively large amounts, wherein said feed premixes or supplements are suitable for direct feeding to the animal or for addition to the feed either directly or after an intermediate dilution or blending step.

Typical carriers or diluents suitable for such compositions include distillers' dried grains, corn meal, citrus meal, fermentation residues, ground oyster shells, wheat products, molasses, corn cob meal, edible bean mill feed, soya grits, crushed limestone and the like. The active compounds are intimately dispersed throughout the carrier by methods such as grinding, stirring, milling or tumbling. Compositions containing about 0.005% to about 2.0%, by weight, of the active compound are particularly suitable as feed premixes.

Feed supplements, which are fed directly to the animal, contain about 0.0002% to 0.3%, by weight, of the active compounds. Such supplements are added to the animal feed in an amount to give the finished feed the concentration of active compound desired for the treatment or control of the resistant parasitic disease. Although the desired concentration of the active compound will vary depending upon a variety of factors such as the particular compound employed or the severity of the affliction, the macrocyclic compounds of this invention are usually fed at concentrations of about 0.00001% to about 0.02% in the feed.

Alternatively, the compounds of the present invention may be administered to the afflicted mammals parenterally, in which event the active ingredient is dissolved, dispersed or suspended in a sterile, isotonic, nontoxic liquid carrier vehicle. The active material is admixed with the nontoxic pharmaceutically acceptable vehicle, preferably a vegetable oil such as peanut oil, cotton seed oil or the like. Other parenteral vehicles such as propylene glycol, glycerol and the like may also be used for parenteral formulations.

In the parenteral formulations, the active macrolides are typically dissolved or suspended in the formulation in sufficient amount to provide from about 0.005% to about 5.0%, by weight, of the active compound in said formulation.

Conveniently, the macrolides may also be administered to the afflicted mammals by the topical or transdermal route to achieve either local or systemic effect. When used on animals, the compounds may be applied as a liquid drench. The animal drench is normally a solution, suspension or dispersion of the active compound, usually in water, together with a suspending agent such as bentonite and a wetting agent or similar excipient. Generally, the drenches also contain all antifoaming agent. Drench formulations typically contain about 0.001% to about 0.5%, by weight, of the active macrocyclic compound. Preferred drench formulations contain about 0.01% to about 0.1%, by weight.

Additionally, the macrocyclic compounds may be administered by applying as a gel, lotion, solution, cream or ointment to human skin or pouring on animal skin or hide via a solution. The topical or transdermal formulations comprise the active ingredient in combination with conventional inactive excipients and carriers. The cream, for example, may use liquid petrolatum, white petrolatum, propylene glycol, stearyl alcohol, cetyl alcohol, sodium lauryl sulfate, sodium phosphate buffer, polysorbates, parabens, emulsifying wax, polyoxyethylene-polyoxypropylene block copolymers, purified water and the like. Ointments, for example, may employ petrolatum, mineral oil, mineral wax, glycerin and the like. Topical solutions may provide the active ingredient compounded with propylene glycol, parabens, hydroxypropyl cellulose, preservatives. Pour-on formulations may constitute the active ingredient dissolved in a suitable inert solvent, such as dimethylsulfoxide, propylene glycol, butoxyethoxyethanol and the like. A particularly useful pour-on formulation comprises the active ingredient dissolved or dispersed in an aromatic solvent, PPG-2 myristyl ether propionate, polybutene, an antimicrobial agent, an antioxidant and a nontoxic pharmaceutically acceptable mineral or vegetable oil.

To increase the efficacy of the macrolides as pesticidal agents, the multidrug resistance reversing agents are applied to crops, crop seeds or the soil or water in which crops or seeds are growing or to be grown in a pesticidal enhancing effective amount. The MDR-reversing agents may be applied either before or concurrently with the application of the macrocyclic lactone. Typically, the MDR-reversing agent will be applied within 4 hours before or, preferably, concomitantly with the application of the macrocyclic lactone.

In terms of application rates, the suitable amount of the MDR-reversing agent which is effective to increase the efficacy of the macrocyclic lactone compound against resistant crop pests will typically vary within a wide range of amounts at a variety of concentrations and rates. The particular MDR-reversing agent selected for use with the crop pesticide will clearly affect the application rate of the MDR-reversing agent. It is contemplated that choice of appropriate amounts, concentrations, spray rates and the like of each MDR-reversing agent and the macrocyclic lactone compound to achieve the pesticidal enhancing effective amount can be easily determined by routine procedures known to those having ordinary skill in the agricultural art.

As insecticidal, nematocidal or acaricidal agents useful for protecting crop seeds or growing or harvested crops from the pest's attack, the compounds of the present invention may be formulated into dry compacted granules, flowable compositions, wettable powders, dusts, dust concentrates, microemulsions and the like, all of which lend themselves to soil, water or foliage application and provide the requisite plant protection. Such compositions include the compounds of the invention admixed with agronomically acceptable solid or liquid carriers.

In the agricultural composition, the active compounds are intimately mixed or ground together with the excipients and carriers in sufficient amounts to typically provide from about 3% to about 20% by weight of the macrocyclic lactone compound in said composition.

The compositions of this invention are useful in combatting agricultural pests that inflict damage upon crops while they are growing or while in storage. The compounds are applied using known techniques such as sprays, dusts, emulsions, wettable powders, flowables and the like to the growing or stored crops to provide protection against infestation by agricultural pests.

Unexpectedly, it is found that the mechanism of resistance to the macrocyclic lactone compounds is due to overexpression of novel P-glycoprotein homologs which causes an efflux of anthelmintic from the parasite. The present invention illustrates the involvement of the Pgp homolog genes in IVM resistance in H. contortus. The overexpression of Pgp-protein in IVM resistant strains of H. contortus is shown to be regulated by both rearrangement of genomic DNA encoding the PGP homologs and by gene transcription.

H. contortus in jirds (Meriones unguiculatus) has been used for the evaluation of anthelmintic efficacy and has been shown to correlate well with studies of this parasite in sheep (Conder et al., J. Parasitol. 78: 492-497, 1992). Employing the jird model, the present invention determines that multidrug reversing agents can unexpectedly be used to increase the efficacy of macrocyclic lactones against resistant parasites. As a representative example, the multidrug resistance (MDR) reversing agent verapamil (VRP) is shown to uniquely enhance the action of moxidectin and ivermectin against moxidectin susceptible and resistant H. contortus.

Parasites such as H. contortus contain Pgp homolog genes which are expressed in different stages of the parasite life cycle. This invention finds that the level of expression of P-glycoprotein is surprisingly elevated in different strains that are resistant to macrocyclic lactones such as ivermectin compared with the levels in the susceptible strains from which the resistant strains are derived. The higher level of Pgp expression, in ivermectin resistant strains, is associated with an alteration at the genomic level.

P-glycoproteins can act as molecular pumps to eff lux hydrophobic xenobiotics from cells. An elevation in the level of the P-glycoproteins is the basis of multidrug resistance in cancer cells and also appears to be involved in some forms of drug resistance in some protozoa. An elevated level of Pgp has not so far been described as the mechanism of drug resistance in nematode parasites. This is the first evidence that shows that ivermectin resistance can be due to an elevation in P-glycoproteins. Ivermectin resistance is becoming a common problem in nematode parasites of animals and potentially in arthropod parasites. Its continued use against arthropods is likely to lead to the selection of similar resistance to that in nematodes.

Evidence exists that ivermectin shares a common action with other avermectins, such as doramectin, milbemycins (Arena et al., 1995) and moxidectin. It can be predicted that the development of resistance against other macrocyclic lactone compounds will involve hyperexpression of P-glycoprotein leading to elevated rates of drug efflux.

This work is significant because it allows the sensitive detection of ivermectin resistance and resistance to other macrocyclic lactone compounds in nematodes and arthropods using DNA and cDNA probes based on the demonstrated differences found in the PvuII digests of DNA from resistant and susceptible organisms. It also permits the prediction of the degree of resistance from the level of P-glycoprotein expression based on either Pgp mRNA or Pgp protein levels. This understanding of the mechanism of resistance to the macrolides allows active analogs to be synthesized which will remain effective in the presence of an mdr-based mechanism of resistance to other macrocyclic lactones. More specifically, chemicals which act on the mode of action receptor, the glutamate-gated chloride channel (Arena et al., 1995), but which are not efficiently ef f luxed by the P-glycoprotein pump, i.e., are poor substrates for Pgp efflux, can be selected to overcome resistance. This will lead to improvements in. parasite controls, especially in the prevention and treatment of ivermectin resistance and cross-resistance to other avermectins, milbemycins and the LL-F28249 compounds.

This invention provides new evidence that in resistance to macrocyclic lactone endectocides, such as ivermectin, in nematode and arthropod parasites of animals, expression of P-glycoprotein is elevated compared with the level of expression in the parental susceptible strains of the parasite. It further shows that the higher level of expression is associated with differences, at the genomic level, of P-glycoprotein genes. For example, using Southern blot analysis of pooled DNA and by PCR (Polymerase Chain Reaction) analysis of individual worms, differences are determined in the genomic DNA for Pgp in Haemonchus contortus resistant to ivermectin compared with the susceptible parental strain, and the allele diversity for Pgp in resistant worms appears to be markedly reduced compared with the parental susceptible strain. Novel nucleic acid probes which can differentiate between susceptible and resistant parasites are now found and deemed to be useful in the early detection of the development of resistance to macrocyclic lactone compounds.

For the first time, this invention demonstrates that macrolactone resistance can be overcome by using a MDR-reversing agent. For example, verapamil, a well-known, relatively weak MDR-reversing agent, significantly increases the efficacy of moxidectin against moxidectin resistant H. contortus. The moxidectin resistant worms show side resistance to ivermectin and the ivermectin resistance is also overcome with the use of a mild MDR-reversing agent. The following examples demonstrate certain aspects of the present invention. However, it is to be understood that these examples are for illustration only and do not purport to be wholly definitive as to conditions and scope of this invention. It should be appreciated that when typical reaction conditions (e.g., temperature, reaction times, etc.) have been given, the conditions which are both above and below the specified ranges can also be used, though generally less conveniently. The examples are conducted at room temperature (about 23° C. to about 28° C.) and at atmospheric pressure. All parts and percents referred to herein are on a weight basis and all temperatures are expressed in degrees centigrade unless otherwise specified.

A further understanding of the invention may be obtained from the following non-limiting examples.

EXAMPLE 1 PCR Synthesis and Cloning of a 432 bp DNA for a P-Glycoprotein Homolog from a cDNA Library of H. contortus

Based on the highly conserved ATP binding domains of C. elegans Pgp, a pair of degenerate PCR primers is designed. The sense primer is 5′-ACNGTNGCNYTNGTNGG-3′ (which corresponds to SEQ ID NO:11) and the antisense primer is 5′-GCNSWNGTNGCYTCRTC-3′ (which corresponds to SEQ ID NO:12). PCR is carried out for 40 cycles at a denaturing temperature of 94° C. for 1 minute, an annealing temperature of 37° C. for 1 minute, and an extension temperature of 72° C. for 3 minutes using an H. contortus cDNA library (Geary et al., Mol. Biochem. Parasitol., 50: 295-306, 1992) as template. A 432 bp product is purified by agarose gel electrophoresis and the purified product is used as template for a second round of PCR amplification with the same primers. An enriched 432 bp product is subsequently cloned into TA vector (Invitrogen) according to standard protocols. Plasmids with inserts are transformed into Escherichia coli and then plated on Ampicillin LB plates containing a chromogenic substrate, X-GAL® (5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, commercially available from Gibco BRL, Bethesda, md.) (Sambrook et al., Molecular Cloning. A Laboratory Manual, 2nd Ed., Cold Spring Harbor Laboratory Press, 1989). Ten clones are identified as ATP binding domain sequences of P-glycoprotein.

EXAMPLE 2 Screening of the H. contortus cDNA Library

The 432 bp fragment is excised by EcoR1, labelled by random priming with [³²P] d-CTP and used as a probe to screen the cDNA library (Sambrook et al., 1989). Approximately one million clones are screened and nine putative clones are identified. The positive clones are digested with PvuII and three of them containing inserts in the predicted size are subsequently sequenced.

EXAMPLE 3 Parasite Strains

Two pairs of ivermectin susceptible and resistant strains of H. contortus are used. The first pair is an ivermectin resistant strain (MFR) developed at the Merck Research Laboratories, Rahway, N.J. (Rohrer et al., J. Parasitol. 80: 493-497, 1994) and the ivermectin susceptible parent strain (MFS) from which the resistant strain is selected over seventeen generations of ivermectin selection. The second pair is an ivermectin resistant strain (ACR) developed at American Cyanamid Company, Princeton, N.J. and the ivermectin susceptible parent strain (ACS) from which the resistant strain is selected over fourteen generations of ivermectin selection. Strain MFR is reported to be 10× resistant at the ED₉₅ compared with MFS, and ACR, after twelve generations of selection, is found to be 6.3× resistant at the ED₉₅ compared with ACS.

EXAMPLE 4 RNA Extraction and Northern Hybridization

Adult worms from ivermectin susceptible and resistant H. contortus are collected from the abomasum of sheep (Lubega and Prichard, Biochem. Pharmacol. 41: 93-101, 1991). Eggs from each strain are collected and isolated from faeces of sheep (Weston et al., J. Parasitol. 14: 159-164, 1984) which have been previously worm free and inoculated with one of the four H. contortus strains. Total RNA is extracted from tissues of the ivermectin susceptible and resistant strains, respectively, using TRIzoL® Reagent (Gibco BRL Life Technologies, Inc., Gaithersburg, Md., company protocol). Total RNA is run on denaturing formaldehyde agarose gel electrophoresis and transferred to H-bond nylon membranes. The membranes are prehybridized at 65° C. in 10% dextran disulfate, 1% SDS (sodium dodecylsulfate), 1.0M NaCl over 4 hours. The ³²P-labelled 432 bp H. contortus Pgp fragment and an actin probe consisting of the 1.25 kb PstI fragment from pBA1 (Degen et al., J. Biol. Chem. 258: 12153, 1983) are mixed and incubated overnight with the membranes at 65° C. in the same hybridization buffer. The membranes are washed with 2×SSC (1:2 mixture of trisodium citrate and sodium chloride), 0.1% SDS at 65° C. for 30 minutes and 0.5×SSC at 35° C. for 1 hour and then autoradiographed. Image analyses of gel autoradiographs are made for quantitative determination of mRNA expression, using the IMAGE program (O'Neil et al., Appl. Theor. Electrophor., 1: 163-167, 1989). Actin DNA probes from a mouse source, labelled and hybridized with the same blot, using the same method as above, is used as an internal control for mRNA loading. Results are shown in FIG. 3 (S=unselected strains; R=IVM selected strains; MKI=strains developed at Merck Research Laboratories, Rahway, N.J.; ACI=strains developed at American Cyanamid Company, Princeton, N.J.).

EXAMPLE 5 Southern Blots

Genomic DNA from both ivermectin susceptible and resistant strains is extracted (Sambrook et al., 1989). Four restriction enzymes EcoRI, ClaI, PvuII and PstI are used to digest the genomic DNA following the suppliers' directions. Each reaction is carried out with both ivermectin resistant and susceptible strains. After an overnight restriction enzyme digestion, samples are run on 1% agarose gels and then blotted onto H-bond membranes (Sambrook et al., 1989). The membranes with DNA are exposed under UV light to fix the DNA to the membranes. The membranes are prehybridized at 65° C. in buffer (10% sulfur dextran, 1% SDS and 1M NaCl) for at least 4 hours. The 432 bp fragment, labelled with [³²P], is added as a probe and hybridized with the genomic DNA in the prehybridization buffer, overnight. The membranes are subsequently washed twice with 2×SCC for 10 minutes, twice with 1×SCC for 15 minutes and then autoradiographed.

RESULTS PCR Amplification

Two rounds of PCR amplification generate a 432 bp product (FIG. 1) which is highly homologous to the conserved ATP binding domain of P-glycoprotein (FIG. 2A). The putative amino acid sequence (FIG. 2B) shows that this fragment is highly homologous to P-glycoprotein or multiple drug resistant proteins from C. elegans, mouse and other species. These data indicate that the 432 bp fragment represents the ATP binding sequence of an H. contortus Pgp homolog.

Expression of P-Glycoprotein mRNA in Ivermectin Resistant and Susceptible Strains of H.contortus

A single animal species may have different Pgp which may vary in size. Northern hybridization, with the 432 bp Pgp H. contortus homolog PCR product, shows that the molecular size of the mRNA for the H. contortus Pgp is about 4 kb. However, it is found that the mRNA levels of Pgp in ivermectin resistant and susceptible strains of H. contortus are different. For illustration, results of a number of representative Northern blots on H. contortus egg RNA are shown in FIG. 3.

The RNA is also probed with an actin probe to allow correction for different amounts of RNA loaded onto the gels. The intensity of the Pgp mRNA band varies with the strain of parasite. After correction for the intensity of the actin band, it is found that the amount of the 4 kb mRNA band recognized by the 432 bp Pgp probe is much higher in both ivermectin resistant strains compared with their respective ivermectin susceptible precursor strains. The increase varies from 250% to 670% after standardization for actin mRNA expression in drug resistant and susceptible strains (Table 1). Similar results are also obtained in comparisons of Pgp expression using RNA extracted from adult H. contortus.

Table 1 shows the relative intensity of mRNA for P-glycoprotein and actin in ivermectin susceptible and resistant Haemonchus contortus strains. RNA is extracted from eggs from the respective Merck (MKI) and American Cyanamid (ACI) paired strains. Each susceptible and resistant pair are processed at the same time. The RNA is separated on an agarose gel and probed with both H. contortus432 bp Pgp and the actin PBA1 radiolabelled probes. The relative intensity of each band is determined, after gel autoradiography, by gel densitometry. The intensity of each Pgp band is corrected for intensity of its corresponding actin band in order to adjust for different amounts of RNA having been loaded onto the gels. All comparisons are made by pairs (resistant (R) versus corresponding susceptible (S)).

TABLE 1 Strains comparison Corrected R/S ratio MKIS/MKIR 6.77 MKIS/MKIR 6.08 MKIS/MKIR 2.57 ACIS/ACIR 4.19

Sequencing of P-Glycoprotein Homologs From the H. contortus cDNA Library

Longer clones (4.2 kb, 3.5 kb and 2.7 kb) identified using the 432 bp probe, which are shown to be homologous to P-glycoprotein, are fully or partially sequenced. FIGS. 4A to 4B show the full cDNA sequence for the PGP-A clone (4175 bp) which has high homology to known P-glycoprotein genes such as the Xenopus putative multidrug resistance protein (Xemdr) and the C. elegans cepgpA gene for P-glycoprotein A. FIGS. 5 and 6 show the partial sequence, in the sense direction (FIG. 5; PGP-A-5′) and the antisense direction (FIG. 6; PGP-A-3′) of the cDNA fragment which is also highly homologous to P-glycoprotein. FIGS. 7-9 illustrate, respectively, the putative amino acid translation of PGP-A cDNA, the partial cDNA sequence of the 3′ end of the PGP-O clone (3.5 kb), antisense direction, and the partial cDNA sequence of 3′ end of the PGP-B clone (2.7 kb), antisense direction.

Genomic DNA Differences Between Ivermectin Resistant and Susceptible Strains of H. contortus and Determination of a Nucleic Acid Probe for the Detection of Macrolactone Susceptibility or Resistance

Genomic DNA hybridizations show that at least two bands are recognized by the 432 bp probe in C1aI and PstI digestion maps of both ivermectin susceptible and resistant strains. The EcoRI digestion maps show three strongly hybridizing bands and one light band for both susceptible and resistant strains. However, the PvuII digestion patterns are clearly different between the ivermectin resistant and susceptible strains (FIG. 10).

PCR products are generated using pairs of primers which are specific to parasite Pgp genes. In one example, the reverse primer is specific for a region 53 base pairs in length present in one of the Pgp clones (PGP-O). The forward primer anneals to a region common to multiple Pgp clones. Genomic DNA extracted from individual male H. contortus adults from IVM-sensitive (24 worms) and IVM-resistant (29 worms) populations (MKIS and MKIR) is used as template for amplification by PCR. The Pgp PCR products, approximately 900 bp in length, are digested with the restriction enzyme DdeI and the digestion products are separated by non-denaturing polyacrylamide gel electrophoresis (FIG. 11; see also FIGS. 17A-18C illustrating diagnostic restriction patterns for resistance after selection with either ivermectin or moxidectin, using different worm strains and different restriction enzymes). The digestion pattern for the worms from the susceptible population is variable, while that for the worms from the resistant population is more homogeneous. An identical digestion pattern of three bands (arrows) is found in 28 of the 29 worms from the resistant population (FIG. 11, lanes 11-18 and 20, for example), whereas only 4 or 5 worms from the susceptible population have this pattern (FIG. 11, lanes 6 and 9, for example). Examples of the probes are shown in FIGS. 12A and 12B.

These results are repeated several times. The PCR data and the Southern blot data clearly indicate that selection for macrocyclic lactone endectocide resistance causes a reduction in the genetic diversity of the Pgp alleles and that the differences in Pgp at the DNA level can be detected by specific probes techniques such as PCR (Polymerase Chain Reaction), Southern blot analysis and RFLP (Restriction Fragment Length Polymorphism).

Additional Methods EXAMPLE 6 Establishing the LD₅₀ for Moxidectin and Ivermectin Against Moxidectin Susceptible and Resistant H. contortus in the Jird

Jirds, which are fed on a standard commercial ration to which 0.02% hydrocortisone has been added 5 days prior to infection, are inoculated with 1000 exsheathed L₃ H. contortus. On day 10 after inoculation, the jirds are treated with either water or various doses of moxidectin or ivermectin orally. Each treatment group contains 6 jirds. The parasite strains and anthelmintic dose rates are shown in Table 2. The results of these dose titrations are shown in FIGS. 13A-14B. Probit analyses are used to estimate LD₅₀ levels for each anthelmintic against each strain. The estimated LD₅₀ of moxidectin against the susceptible and moxidectin resistant strains are 0.010 and 0.017 mg/kg, respectively, and for ivermectin the estimate LD₅₀ levels are 0.024 and 0.046 mg/kg, respectively.

The results indicate that (i) moxidectin is more potent than ivermectin against both the susceptible and moxidectin resistant strains, and (ii) moxidectin resistant H. contortus are side-resistant to ivermectin.

TABLE 2 DOSE RATES (mg/kg) OF MOXIDECTIN (MOX) OR IVERMECTIN (IVM) AGAINST H. contortus MOX-RESISTANT AND SUSCEPTIBLE STRAINS IN JIRDS (n = 6) COMPOUND (mg/kg) SUSCEPTIBLE (PF14) RESISTANT (MOF14) CONTROL — — MOX 0.0125 0.0125 MOX 0.025 0.025 MOX 0.05 0.05 MOX 0.1 0.1 IVM 0.025 0.025 IVM 0.1 0.1 IVM 0.4 0.4 IVM 1.6 1.6

EXAMPLE 7 Determination of the Toxicity and the Efficacy of Verapamil Alone and in Combination with Ivermectin

This experiment is performed to determine the toxicity of verapamil, a weak MDR-reversing agent, alone and in combination with ivermectin, the efficacy of verapamil alone against H. contortus and the effect of verapamil at 20 mg/kg on the efficacy of ivermectin against susceptible and moxidectin resistant worms. Dose rates of verapamil between 20 and 80 mg/kg are used alone or in combination with ivermectin at 0.024 and 0.046 mg/kg in jirds infected with susceptible or moxidectin resistant H. contortus. Verapamil is given concomitantly with ivermectin by the oral route. The results are shown in Table 3.

TABLE 3 DEMONSTRATION OF TOXICITY AND EFFICACY OF VERAPAMIL (VRP) WITH OR WITHOUT IVERMECTIN AGAINST H. contortus MOXIDECTIN RESISTANT OR SUSCEPTIBLE STRAINS IN JIRDS (n = # per group) COMPOUND # SUSCEPTIBLE # RESISTANT (mg/kg) (PF14) (MOF14) CONTROL 5 5 VRP 20 5 5 VRP 40 3 3 VRP 60 3 3 VRP 80 3 3 IVM** 5 5 IVM/VRP 20 5 5 IVM/VRP 40 5 5 IVM/VRP 60 5 5 IVM/VRP 80 5 5 **The dose of ivermectin is 0.024 mg/kg against strain PF14 and 0.046 mg/kg against strain MOF14.

As no deaths or other signs of toxicity are observed at a verapamil dose rate of 20 mg/kg, in the absence or presence of ivermectin, this dose rate is used for subsequent resistance reversing experiments. Verapamil alone is found to have no significant effect on worm counts at any of the dose rates used.

The toxicity of verapamil is summarized in Table 4.

TABLE 4 TOXICITY OF VERAPAMIL TO JIRDS VRP (mg/kg) DEATHS - VRP ALONE DEATHS - VRP + IVM* 20  0/10 1/10 40 0/5 2/10 60 1/6 1/10 80 3/7 2/10 *Ivermectin is used at 0.24 mg/kg or 0.046 mg/kg according to Table 3.

Because of the toxicity of verapamil at dose rates of 40 mg/kg and above, only the effects of verapamil at 20 mg/kg on the efficacy of ivermectin against susceptible and moxidectin resistant worms are considered. These results, shown in FIGS. 15A and 15B, are summarized in Table 5. Verapamil at 20 mg/kg significantly enhances the efficacy of ivermectin against the moxidectin resistant worms.

TABLE 5 EFFECT OF VERAPAMIL (20 mg/kg) ON THE EFFICACY (%) OF IVERMECTIN SUSCEPTIBLE MOX-RESISTANT STRAIN (PF14) (MOF14) TREATMENT (mg/kg) % EFFICACY* % EFFICACY* CONTROL 0 0 VRP 20 17 (n.s.) −53 (n.s.) IVM^(#) 54 (A) 79 (A) IVM^(#)/VRP 20 92 (A) 96 (B) ^(#)Ivermectin is administered at 0.024 mg/kg to jirds infected with PF14 strain and at 0.046 mg/kg to jirds infected with the MOF14 strain. “n.s.” indicates that the worm counts are not significantly different from the controls; “A” means significantly different from the controls, but not from other worm counts, of the same strain, with the same letter; “B” means significantly different worm counts from “A” for the same strain and dose rate of ivermectin.

EXAMPLE 8 The Effects of Verapamil on the Efficacy of Moxidectin and Ivermectin Against Susceptible and Moxidectin Resistant H. contortus

This experiment is performed on jirds to determine the effects of verapamil at 20 mg/kg on the efficacy of moxidectin and ivermectin against susceptible and moxidectin resistant H. contortus. All treatments have 7 jirds/group. The dose rates of moxidectin and ivermectin are selected to give approximately 50% efficacy in the absence of verapamil. Verapamil at 20 mg/kg significantly increases the efficacy of moxidectin against the resistant worms. The increase observed when verapamil is coadministered with ivermectin is not significant in this experiment as the efficacy obtained with ivermectin alone is already relatively high. The results are shown in Table 6 (see graphic representation of results in FIGS. 16A and 16B).

TABLE 6 EFFECT OF VERAPAMIL ON THE EFFICACY (%) OF MOXIDECTIN AND IVERMECTIN AGAINST THE MOXIDECTIN-RESISTANT STRAIN OF H. contortus (MOF14) EFFICACY (%) WORM COUNTS SIGNIFICANCE TREATMENT (MEAN ± S.E.) AT P < 0.05 PLACEBO 46 ± 7  — A# VRP* 80 ± 9  −73 A MOX (0.017 mg/kg) 14 ± 3  70 B MOX (0.017 mg/kg) 2 ± 1 96 C + VRP* IVM (0.028 mg/kg) 9 ± 1 80 B IVM (0.028 mg/kg) 3 ± 1 93 B + VRP* *Verapamil is administered at 20 mg/kg. All treatments are by the oral route. # Different letters indicate the mean worm counts are statistically different. However, the ivermectin (±verapamil) results are not compared with the moxidectin (±verapamil) results. Verapamil by itself increases worm counts, but the mean count is not statistically different from the control.

This experiment confirms that the weak MDR-reversing agent verapamil overcomes resistance in nematodes to the macrolactones. These results are fully consistent with the above molecular evidence that macrolactone resistance is associated with the overexpression of P-glycoprotein homolog due to a change in P-glycoprotein DNA in resistant parasites. More potent MDR-reversing agents, such as cyclosporin A, SDZ-PSC 833 or other potent reversing agents can, at low dose rates, markedly increase the efficacy of macrocyclic lactone endectocides against resistant parasites.

In the foregoing, there has been provided a detailed description of particular embodiments of the present invention for the purpose of illustration and not limitation. It is to be understood that all other modifications, ramifications and equivalents obvious to those having skill in the art based on this disclosure are intended to be included within the scope of the invention as claimed.

12 432 base pairs nucleic acid double linear cDNA 1 ACGGTGGCGT TTGTTGGGCA GTCTGGTTGT GGAAAAAGCA CTGTGAAGGC GTTGTTGGAC 60 GGTTTTACAA TCAAAACAAG GGCGTGATTA CGGACGCCGA AAACATCAGA AACATGAACA 120 TACGCAATCT TCGTGAGCAA GTGTGTATTG TAAGCCAGGA ACCAACGCTG TTCGACTGTA 180 CCATCATGGA AAACATCTGT TACGGTCTCG ATCGACCCCA AGCTCCTACG AACAGGTTGT 240 TGCTGCAGCA AAATCGGTCG AGTCGAAATG GCGAACATTC ACAATTTTGT GCTGGGACTA 300 CCAGAGGGTT ACGATACGCG TGTTGGTGAG AAAGGCACTC AGCTGTCAGG CGGACAGAAG 360 AAACGAATAG CCATAGCCAG AGCGCTGATT CGAGATCCGC CTATACTTCT GCTGGATGAG 420 GCTACGACGG CC 432 144 amino acids amino acid single linear protein 2 Thr Val Ala Phe Val Gly Gln Ser Gly Cys Gly Lys Ser Thr Val Lys 1 5 10 15 Ala Leu Leu Glu Arg Phe Tyr Asn Gln Asn Lys Gly Val Ile Thr Asp 20 25 30 Ala Glu Asn Ile Arg Asn Met Asn Ile Arg Asn Leu Arg Glu Gln Val 35 40 45 Cys Ile Val Ser Gln Glu Pro Thr Leu Phe Asp Cys Thr Ile Met Glu 50 55 60 Asn Ile Cys Tyr Gly Leu Asp Asp Pro Lys Leu Leu Arg Thr Gly Cys 65 70 75 80 Cys Cys Ser Lys Ile Gly Arg Val Glu Met Ala Asn Ile His Asn Phe 85 90 95 Val Leu Gly Leu Pro Glu Gly Tyr Asp Thr Arg Val Gly Glu Lys Gly 100 105 110 Thr Gln Leu Ser Gly Gly Gln Lys Lys Arg Ile Ala Ile Ala Arg Ala 115 120 125 Leu Ile Arg Asp Pro Pro Ile Leu Leu Leu Asp Glu Ala Thr Thr Ala 130 135 140 4175 base pairs nucleic acid double linear cDNA 3 GGTTTAATTA CCCAAGTTTG AGAGATCGTT CTCAAGCTGG TAAAATGTTC GAAAAAGGCC 60 AAGATGATGA ACGTATACCA TTACTCGGTT CATCCAAGAA AAGTTCAATC GGCGAAGTCA 120 GTAAAAAAGA AGAACCGCCT ACAATAACAA ACCGTGGAAT TCTCTCCTTA GCCACTACAT 180 TGGATTATGT GCTTCTTGCG GCTGGTACGC TGGCGCCGTG TGTTCATGGC GCTGGATTCT 240 CAGTACTCGG TATTGTACTC GGTGGTATGA CGACAGTCTT TCTCAGAGCT CAGAACTCAG 300 AATTCGTTCT GGGCACTGTT AGTCGGGATC CTGAAGGGCT ACCAGCTCTT ACTAAGGAAG 360 AATTTGACAC ACTAGTACGT AGGTATTGCT TATACTACCT TGGATTAGGC TTTGCTATGT 420 TTGCAACATC TTATATACAG ATTGTGTGTT GGGAGACGTT CGCCGAACGA ATTACCCATA 480 AATTACGAAA AATTTATCTA AAAGCCATAC TTCGGCAGCA GATCTCATGG TTTGACATTC 540 AACAAACAGG AAATCTCACA GCTCGTCTAA CCGATGATCT CGAACGTGTT CGTGAAGGAC 600 TTGGTGATAA ACTGTCGCTT TTTATACAAA TGGTGTCTGC TTTTGTGGCT GGTTTCTGTG 660 TAGGATTCGC GTATAGCTGG TCAATGACGC TCGTGATGAT GGTCGTGGCG CCGTTTATAG 720 TTATTTCTGC TAATTGGATG TCAAAAATCG TTGCTACTAG GACCCAAGTT GAACAGGAAA 780 CCTACGCTGT TGCCGGTGCT ATAGCGGAGG AGACTTTCTC ATCGATACGA ACCGTACACT 840 CGATATGTGG CCATAAAAGA GAGCTAACAA GATTTGAGGC AGCGTTGGAG AAAGGACGTC 900 AGACAGGCCT TGTCAAATAT TTCTATATGG GTGTTGGTGT GGGATTTGGT CAGATGTGTA 960 CCTATGTGTC CTACGCCTTG GCTTTTTGGT ATGGCAGTGT ACTGATCATC AACGACCCTG 1020 CATTGGATCG TGGCCGAATT TTCACAGTCT TTTTTGCTGT GATGTCCGGC TCAGCAGCTC 1080 TCGGCACATG TCTGCCACAT CTTAACACCA TATCCATCGC TCGAGGAGCG GTACGAAGTG 1140 TACTGTCAGT GATTAATAGT CGTCCAAAAA TCGATCCCTA TTCGTTAGAT GGCATTGTGC 1200 TCAACAATAT GAGAGGATCT ATCCGCTTCA AGAACGTGCA TTTCTCCTAT CCTTCCCGAA 1260 GAACATTGCA GATATTGAAA GGTGTGTCAC TGCAAGTGTC GGCTGGCCAA AAAATTGCTT 1320 TGGTGGGTTC AAGCGGTTGT GGAAAGTCAA CGAACGTCAA TTTATTATTG AGATTTTATG 1380 ATCCGACAAG GGGAAAGGTA ACCATAGATG ATATTGATGT GTGTGATCTC AACGTGCAAA 1440 AACTTCGTGA ACAAATCGGT GTTGTTAGTC AGGAACCAGT GCTTTTCGAT GGCACACTAT 1500 TCGAAAATAT CAAGATGGGT TATGAACAGG CCACAATGGA GGAGGTCCAA GAAGCGTGCC 1560 GTGTGGCGAA TGCTGCCGAC TTCACCAAAC GACTTCCAGA AGGTTACGGC ACCCGAGTTG 1620 GTGAACGTGG TGTGCAGTTA AGTGGCGGAC AAAAGCAGCG AATTGCCATA GCTCGTGCGA 1680 TCATCAAGAA CCCTCGCATA CTGCTGCTCG ATGAAGCCAC CAGTGCTCTA GACACAGAAG 1740 CGGAATCAAT CGTGCAAGAG GCTCTGGAGA AGGCTCAAAA AGGGAGAACA ACCGTCATTG 1800 TAGCGCATCG TCTGTCTACT ATCAGAAACG TGGATCAGAT TTTCGTTTTC AAGAACGGAA 1860 CGATCGTTGA GCAGGGCACT CATGCCGAGT TGATGAACAA ACGTGGAGTA TTCTTTGAAA 1920 TGACTCAAGC ACAAGTCCTC CGACAAGAGA AGGAAGAGGA AGTTTTAGAT AGCGATGCGG 1980 AATCCGATGT CGTGTCACCG GATATTGCAT TACCCCATCT TAGTTCACTT CGATCCCGTA 2040 AAGAATCCAC AAGAAGTGCT ATCTCCGCGG TCCCCAGCGT TCGAAGTATG CAAATCGAAA 2100 TGGAGGACCT TCGTGCCAAA CCAACTCCAA TGTCGAAAAT TTTCTATTTT AACCGTGACA 2160 AATGGGGATA TTTCATTTTG GGACTCATCG CCTGTATTAT TACTGGAACT GTTACACCGA 2220 CATTTGCAGT TTTATATGCG CAGATCATAC AGGTATACTC GGAACCTGTT GATCAAATGA 2280 AAGGCCATGT GCTGTTCTGG TGTGGAGCTT TCATCGTCAT TGGTCTCGTA CACGCTTTTG 2340 CGTTCTTTTT CTCGGCTATT TGTTTGGGAC GTTGCGGCGA AGCGTTAACG AAAAAATTAC 2400 GTTTCGAGGC GTTCAAGAAC CTTCTGCGAC AGAATGTGGG ATTCTACGAC GATATCCGAC 2460 ACGGTACCGG TAAACTCTGT ACGCGATTTG CTACAGATGC ACCCAATGTC CGATATGTGT 2520 TCACTCGACT TCCGGGTGTG CTTTCATCGG TGGTGACCAT AATTGGAGCT TTGGTTATTG 2580 GATTCATCTT CGGGTGGCAG CTGGCTTTGA TTCTTATGGT GATGGTACCG TTGATCATCG 2640 GTAGTGGATA CTTCGAGATG CGCATGCAGT TTGGTAAGAA GATGCGTGAC ACAGAGCTTC 2700 TTGAAGAGGC TGGGAAAGTT GCCTCTCAAG CCGTGGAGAA CATTCGTACC GTGCATGCCC 2760 TGAATAGGCA AGAGCAGTTC CATTTCATGT ATTGCGAGTA TTTGAAGGAA CCCTATCGAG 2820 AAAATCTTTG CCAGGCGCAC ACCTACGGGG GTGTATTCGC GTTCTCACAA TCGTTGTTAT 2880 TCTTTATGTA TGCTGTAGCA TTTTGGATTG GTGCAATCTT CGTGGACAAC CACAGCATGC 2940 AACCGATTGA CGTTTACCGA GTATTTTTCG CGTTCATGTT TTGTGGACAA ATGGTCGGCA 3000 ACATTTCTTC TTTTATTCCT GACGTTGTGA AAGCTCGCCT GGCTGCATCG CTCCTTTTCT 3060 ACCTTATCGA ACACCCATCA GAAATTGATA ATTTGTCCGA GGATGGTGTC ACGAAGAAAA 3120 TCTCTGGTCA TATCTCGTTC CGCAATGTCT ATTTCAATTA TCCGACAAGA AGACAGATCA 3180 GAGTACTCCG TGGACTTAAC CTAGAGATAA ATCCTGGCAC GACGGTAGCG CTTGTTGGGC 3240 AGTCTGGTTG TGGAAAAAGC ACTGTGATGG CGTTGTTGGA ACGGTTTTAC AATCAAAACA 3300 AGGGCGTGAT TACGGTGGAC GGCGAAAACA TCAGAAACAT GAACATACGC AATCTTCGTG 3360 AGCAAGTGTG TATTGTTAGC CAGGAACCAA CGCTGTTCGA CTGTACCATC ATGGAAAACA 3420 TCTGTTACGG TCTCGATGAC CCCAAGCCGT CCTACGAACA GGTTGTTGCT GCAGCAAAAA 3480 TGGCGAACAT TCACAATTTT GTGCTGGGAC TACCAGAGGG TTACGATACG CGTGTTGGTG 3540 ARAAAGGCAC TCAGCTGTCA GGCGGACAGA AGCAACGAAT AGCCATAGCC AGAGCGCTGA 3600 TTCGAGATCC GCCTATACTT CTGCTGGATG AGGCGACAAG CGCGCTGGAT ACCGAGAGTG 3660 AAAAGATCGT GCAAGACGCC CTAGAGGTTG CTCGCCAAGG TAGAACGTGC CTTGTAATTG 3720 CCCATCGCCT TTCTACAATT CAAGACAGTG ACGTCATAGT GATGATCCAG GAGGGGAAAG 3780 CTACAGACAG AGGCACTCAT GAACATTTAC TGATGAAGAA CGATCTATAC AAACGGCTAT 3840 GCGAAACACA ACGACTCGTT GAATCACAAT GAGTTTTTAG TGCCAATCGA TAGTGATCGA 3900 TAAGCTATGG ATTAGTCTTT AACACTTACT GATCATATGA CTCTATCTCG TGCTTTATTA 3960 TAATGTACAT ATGTAATGGT TTTGATCTTA CATATCTTGT AATTGGTCCT CACTATCATA 4020 ATGCCTTTAG TAGTATATTA ACAGTTTTAT TAATACAACT TAAGTAACAT ATTAACAATT 4080 TTATTAATAT AACTTAAGTA AGATATTGAC AGTTTTATTA ATTTGGAGGA TTTATAATAA 4140 AACCTCGTGC CGCTCGTGCC GAAACGATAT CAAGC 4175 1810 base pairs nucleic acid double linear cDNA 4 GGTTTAATTA CCCAAGTTTG AGAGATCGTT CTCAAGCTGG TAAAATGTTC GAAAAAGGCC 60 AAGATGATGA ACGTATACCA TTACTCGGTT CATCCAAGAA AAGTTCAATC GGCGAAGTCA 120 GTAAAAAAGA AGAACCGCCT ACAATAACAA ACCGTGGAAT TCTCTCCTTA GCCACTACAT 180 TGGATTATGT GCTTCTTGCG GCTGGTACGC TGGCGCCGTG TGTTCATGGC GCTGGATTCT 240 CAGTACTCGG TATTGTACTC GGTGGTATGA CGACAGTCTT TCTCAGAGCT CAGAACTCAG 300 AATTCGTTCT GGGCACTGTT AGTCGGGATC CTGAAGGGCT ACCAGCTCTT ACTAAGGAAG 360 AATTTGACAC ACTAGTACGT AGGTATTGCT TATACTACCT TGGATTAGGC TTTGCTATGT 420 TTGCAACATC TTATATACAG ATTGTGTGTT GGGAGACGTT CGCCGAACGA ATTACCCATA 480 AATTACGAAA AATTTATCTA AAAGCCATAC TTCGGCAGCA GATCTCATGG TTTGACATTC 540 AACAAACAGG AAATCTCACA GCTCGTCTAA CCGATGATCT CGAACGTGTT CGTGAAGGAC 600 TTGGTGATAA ACTGTCGCTT TTTATACAAA TGGTGTCTGC TTTTGTGGCT GGTTTCTGTG 660 TAGGATTCGC GTATAGCTGG TCAATGACGC TCGTGATGAT GGTCGTGGCG CCGTTTATAG 720 TTATTTCTGC TAATTGGATG TCAAAAATCG TTGCTACTAG GACCCAAGTT GAACAGGAAA 780 CCTACGCTGT TGCCGGTGCT ATAGCGGAGG AGACTTTCTC ATCGATACGA ACCGTACACT 840 CGATATGTGG CCATAAAAGA GAGCTAACAA GATTTGAGGC AGCGTTGGAG AAAGGACGTC 900 AGACAGGCCT TGTCAAATAT TTCTATATGG GTGTTGGTGT GGGATTTGGT CAGATGTGTA 960 CCTATGTGTC CTACGCCTTG GCTTTTTGGT ATGGCAGTGT ACTGATCATC AACGACCCTG 1020 CATTGGATCG TGGCCGAATT TTCACAGTCT TTTTTGCTGT GATGTCCGGC TCAGCAGCTC 1080 TCGGCACATG TCTGCCACAT CTTAACACCA TATCCATCGC TCGAGGAGCG GTACGAAGTG 1140 TACTGTCAGT GATTAATAGT CGTCCAAAAA TCGATCCCTA TTCGTTAGAT GGCATTGTGC 1200 TCAACAATAT GAGAGGATCT ATCCGCTTCA AGAACGTGCA TTTCTCCTAT CCTTCCCGAA 1260 GAACATTGCA GATATTGAAA GGTGTGTCAC TGCAAGTGTC GGCTGGCCAA AAAATTGCTT 1320 TGGTGGGTTC AAGCGGTTGT GGAAAGTCAA CGAACGTCAA TTTATTATTG AGATTTTATG 1380 ATCCGACAAG GGGAAAGGTA ACCATAGATG ATATTGATGT GTGTGATCTC AACGTGCAAA 1440 AACTTCGTGA ACAAATCGGT GTTGTTAGTC AGGAACCAGT GCTTTTCGAT GGCACACTAT 1500 TCGAAAATAT CAAGATGGGT TATGAACAGG CCACAATGGA GGAGGTCCAA GAAGCGTGCC 1560 GTGTGGCGAA TGCTGCCGAC TTCACCAAAC GACTTCCAGA AGGTTACGGC ACCCGAGTTG 1620 GTGAACGTGG TGTGCAGTTA AGTGGCGGAC AAAAGCAGCG AATTGCCATA GCTCGTGCGA 1680 TCATCAAGAA CCCTCGCATA CTGCTGCTCG ATGAAGCCAC CAGTGCTCTA GACACAGAAG 1740 CGGAATCAAT CGTGCAAGAG GCTCTGGAGA AGGCTCAAAA AGGGAGAACA ACCGTCATTG 1800 TAGCGCATCG 1810 2698 base pairs nucleic acid double linear cDNA 5 AGTGCTTTTC GATGGCACAC TATTCGAAAA TATCAAGATG GGTTATGAAC AGGCCACAAT 60 GGAGGAGGTC CAAGAAGCGT GCCGTGTGGC GAATGCTGCC GACTTCACCA AACGACTTCC 120 AGAAGGTTAC GGCACCCGAG TTGGTGAACG TGGTGTGCAG TTAAGTGGCG GACAAAAGCA 180 GCGAATTGCC ATAGCTCGTG CGATCATCAA GAACCCTCGC ATACTGCTGC TCGATGAAGC 240 CACCAGTGCT CTAGACACAG AAGCGGAATC AATCGTGCAA GAGGCTCTGG AGAAGGCTCA 300 AAAAGGGAGA ACAACCGTCA TTGTAGCGCA TCGTCTGTCT ACTATCAGAA ACGTGGATCA 360 GATTTTCGTT TTCAAGAACG GAACGATCGT TGAGCAGGGC ACTCATGCCG AGTTGATGAA 420 CAAACGTGGA GTATTCTTTG AAATGACTCA AGCACAAGTC CTCCGACAAG AGAAGGAAGA 480 GGAAGTTTTA GATAGCGATG CGGAATCCGA TGTCGTGTCA CCGGATATTG CATTACCCCA 540 TCTTAGTTCA CTTCGATCCC GTAAAGAATC CACAAGAAGT GCTATCTCCG CGGTCCCCAG 600 CGTTCGAAGT ATGCAAATCG AAATGGAGGA CCTTCGTGCC AAACCAACTC CAATGTCGAA 660 AATTTTCTAT TTTAACCGTG ACAAATGGGG ATATTTCATT TTGGGACTCA TCGCCTGTAT 720 TATTACTGGA ACTGTTACAC CGACATTTGC AGTTTTATAT GCGCAGATCA TACAGGTATA 780 CTCGGAACCT GTTGATCAAA TGAAAGGCCA TGTGCTGTTC TGGTGTGGAG CTTTCATCGT 840 CATTGGTCTC GTACACGCTT TTGCGTTCTT TTTCTCGGCT ATTTGTTTGG GACGTTGCGG 900 CGAAGCGTTA ACGAAAAAAT TACGTTTCGA GGCGTTCAAG AACCTTCTGC GACAGAATGT 960 GGGATTCTAC GACGATATCC GACACGGTAC CGGTAAACTC TGTACGCGAT TTGCTACAGA 1020 TGCACCCAAT GTCCGATATG TGTTCACTCG ACTTCCGGGT GTGCTTTCAT CGGTGGTGAC 1080 CATAATTGGA GCTTTGGTTA TTGGATTCAT CTTCGGGTGG CAGCTGGCTT TGATTCTTAT 1140 GGTGATGGTA CCGTTGATCA TCGGTAGTGG ATACTTCGAG ATGCGCATGC AGTTTGGTAA 1200 GAAGATGCGT GACACAGAGC TTCTTGAAGA GGCTGGGAAA GTTGCCTCTC AAGCCGTGGA 1260 GAACATTCGT ACCGTGCATG CCCTGAATAG GCAAGAGCAG TTCCATTTCA TGTATTGCGA 1320 GTATTTGAAG GAACCCTATC GAGAAAATCT TTGCCAGGCG CACACCTACG GGGGTGTATT 1380 CGCGTTCTCA CAATCGTTGT TATTCTTTAT GTATGCTGTA GCATTTTGGA TTGGTGCAAT 1440 CTTCGTGGAC AACCACAGCA TGCAACCGAT TGACGTTTAC CGAGTATTTT TCGCGTTCAT 1500 GTTTTGTGGA CAAATGGTCG GCAACATTTC TTCTTTTATT CCTGACGTTG TGAAAGCTCG 1560 CCTGGCTGCA TCGCTCCTTT TCTACCTTAT CGAACACCCA TCAGAAATTG ATAATTTGTC 1620 CGAGGATGGT GTCACGAAGA AAATCTCTGG TCATATCTCG TTCCGCAATG TCTATTTCAA 1680 TTATCCGACA AGAAGACAGA TCAGAGTACT CCGTGGACTT AACCTAGAGA TAAATCCTGG 1740 CACGACGGTA GCGCTTGTTG GGCAGTCTGG TTGTGGAAAA AGCACTGTGA TGGCGTTGTT 1800 GGAACGGTTT TACAATCAAA ACAAGGGCGT GATTACGGTG GACGGCGAAA ACATCAGAAA 1860 CATGAACATA CGCAATCTTC GTGAGCAAGT GTGTATTGTT AGCCAGGAAC CAACGCTGTT 1920 CGACTGTACC ATCATGGAAA ACATCTGTTA CGGTCTCGAT GACCCCAAGC CGTCCTACGA 1980 ACAGGTTGTT GCTGCAGCAA AAATGGCGAA CATTCACAAT TTTGTGCTGG GACTACCAGA 2040 GGGTTACGAT ACGCGTGTTG GTGARAAAGG CACTCAGCTG TCAGGCGGAC AGAAGCAMCG 2100 AATAGCCATA GCCAGAGCGC TGATTCGAGA TCCGCCTATA CTTCTGCTGG ATGAGGCGAC 2160 AAGCGCGCTG GATACCGAGA GTGAAAAGAT CGTGCAAGAC GCCCTAGAGG TTGCTCGCCA 2220 AGGTAGAACG TGCCTTGTAA TTGCCCATCG CCTTTCTACA ATTCAAGACA GTGACGTCAT 2280 AGTGATGATC CAGGAGGGGA AAGCTACAGA CAGAGGCACT CATGAACATT TACTGATGAA 2340 GAACGATCTA TACAAACGGC TATGCGAAAC ACAACGACTC GTTGAATCAC AATGAGTTTT 2400 TAGTGCCAAT CGATAGTGAT CGATAAGCTA TGGATTAGTC TTTAACACTT ACTGATCATA 2460 TGACTCTATC TCGTGCTTTA TTATAATGTA CATATGTAAT GGTTTTGATC TTACATATCT 2520 TGTAATTGGT CCTCACTATC ATAATGCCTT TAGTAGTATA TTAACAGTTT TATTAATACA 2580 ACTTAAGTAA CATATTAACA ATTTTATTAA TATAACTTAA GTAAGATATT GACAGTTTTA 2640 TTAATTTGGA GGATTTATAA TAAAACCTCG TGCCGCTCGT GCCGAAACGA TATCAAGC 2698 1275 amino acids amino acid single linear protein 6 Met Phe Glu Lys Gly Gln Asp Asp Glu Arg Ile Pro Leu Leu Gly Ser 1 5 10 15 Ser Lys Lys Ser Ser Ile Gly Glu Val Ser Lys Lys Glu Glu Pro Pro 20 25 30 Thr Ile Thr Asn Arg Gly Ile Leu Ser Leu Ala Thr Thr Leu Asp Tyr 35 40 45 Val Leu Leu Ala Ala Gly Thr Leu Ala Pro Cys Val His Gly Ala Gly 50 55 60 Phe Ser Val Leu Gly Ile Val Leu Gly Gly Met Thr Thr Val Phe Leu 65 70 75 80 Arg Ala Gln Asn Ser Glu Phe Val Leu Gly Thr Val Ser Arg Asp Pro 85 90 95 Glu Gly Leu Pro Ala Leu Thr Lys Glu Glu Phe Asp Thr Leu Val Arg 100 105 110 Arg Tyr Cys Leu Tyr Tyr Leu Gly Leu Gly Phe Ala Met Phe Ala Thr 115 120 125 Ser Tyr Ile Gln Ile Val Cys Trp Glu Thr Phe Ala Glu Arg Ile Thr 130 135 140 His Lys Leu Arg Lys Ile Tyr Leu Lys Ala Ile Leu Arg Gln Gln Ile 145 150 155 160 Ser Trp Phe Asp Ile Gln Gln Thr Gly Asn Leu Thr Ala Arg Leu Thr 165 170 175 Asp Asp Leu Glu Arg Val Arg Glu Gly Leu Gly Asp Lys Leu Ser Leu 180 185 190 Phe Ile Gln Met Val Ser Ala Phe Val Ala Gly Phe Cys Val Gly Phe 195 200 205 Ala Tyr Ser Trp Ser Met Thr Leu Val Met Met Val Val Ala Pro Phe 210 215 220 Ile Val Ile Ser Ala Asn Trp Met Ser Lys Ile Val Ala Thr Arg Thr 225 230 235 240 Gln Val Glu Gln Glu Thr Tyr Ala Val Ala Gly Ala Ile Ala Glu Glu 245 250 255 Thr Phe Ser Ser Ile Arg Thr Val His Ser Ile Cys Gly His Lys Arg 260 265 270 Glu Leu Thr Arg Phe Glu Ala Ala Leu Glu Lys Gly Arg Gln Thr Gly 275 280 285 Leu Val Lys Tyr Phe Tyr Met Gly Val Gly Val Gly Phe Gly Gln Met 290 295 300 Cys Thr Tyr Val Ser Tyr Ala Leu Ala Phe Trp Tyr Gly Ser Val Leu 305 310 315 320 Ile Ile Asn Asp Pro Ala Leu Asp Arg Gly Arg Ile Phe Thr Val Phe 325 330 335 Phe Ala Val Met Ser Gly Ser Ala Ala Leu Gly Thr Cys Leu Pro His 340 345 350 Leu Asn Thr Ile Ser Ile Ala Arg Gly Ala Val Arg Ser Val Leu Ser 355 360 365 Val Ile Asn Ser Arg Pro Lys Ile Asp Pro Tyr Ser Leu Asp Gly Ile 370 375 380 Val Leu Asn Asn Met Arg Gly Ser Ile Arg Phe Lys Asn Val His Phe 385 390 395 400 Ser Tyr Pro Ser Arg Arg Thr Leu Gln Ile Leu Lys Gly Val Ser Leu 405 410 415 Gln Val Ser Ala Gly Gln Lys Ile Ala Leu Val Gly Ser Ser Gly Cys 420 425 430 Gly Lys Ser Thr Asn Val Asn Leu Leu Leu Arg Phe Tyr Asp Pro Thr 435 440 445 Arg Gly Lys Val Thr Ile Asp Asp Ile Asp Val Cys Asp Leu Asn Val 450 455 460 Gln Lys Leu Arg Glu Gln Ile Gly Val Val Ser Gln Glu Pro Val Leu 465 470 475 480 Phe Asp Gly Thr Leu Phe Glu Asn Ile Lys Met Gly Tyr Glu Gln Ala 485 490 495 Thr Met Glu Glu Val Gln Glu Ala Cys Arg Val Ala Asn Ala Ala Asp 500 505 510 Phe Thr Lys Arg Leu Pro Glu Gly Tyr Gly Thr Arg Val Gly Glu Arg 515 520 525 Gly Val Gln Leu Ser Gly Gly Gln Lys Gln Arg Ile Ala Ile Ala Arg 530 535 540 Ala Ile Ile Lys Asn Pro Arg Ile Leu Leu Leu Asp Glu Ala Thr Ser 545 550 555 560 Ala Leu Asp Thr Glu Ala Glu Ser Ile Val Gln Glu Ala Leu Glu Lys 565 570 575 Ala Gln Lys Gly Arg Thr Thr Val Ile Val Ala His Leu Arg Ser Thr 580 585 590 Ile Arg Asn Val Asp Gln Ile Phe Val Phe Lys Asn Gly Thr Ile Val 595 600 605 Glu Gln Gly Thr His Ala Glu Leu Met Asn Lys Arg Gly Val Phe Phe 610 615 620 Glu Met Thr Gln Ala Gln Val Leu Arg Gln Glu Lys Glu Glu Glu Val 625 630 635 640 Leu Asp Ser Asp Ala Glu Ser Asp Val Val Ser Pro Asp Ile Ala Leu 645 650 655 Pro His Leu Ser Ser Leu Arg Ser Arg Lys Glu Ser Thr Arg Ser Ala 660 665 670 Ile Ser Ala Val Pro Ser Val Arg Ser Met Gln Ile Glu Met Glu Asp 675 680 685 Leu Arg Ala Lys Pro Thr Pro Met Ser Lys Ile Phe Tyr Phe Asn Arg 690 695 700 Asp Lys Trp Gly Tyr Phe Ile Leu Gly Leu Ile Ala Cys Ile Ile Thr 705 710 715 720 Gly Thr Val Thr Pro Thr Phe Ala Val Leu Tyr Ala Gln Ile Ile Gln 725 730 735 Val Tyr Ser Glu Pro Val Asp Gln Met Lys Gly His Val Leu Phe Trp 740 745 750 Cys Gly Ala Phe Ile Val Ile Gly Leu Val His Ala Phe Ala Phe Phe 755 760 765 Phe Ser Ala Ile Cys Leu Gly Arg Cys Gly Glu Ala Leu Thr Lys Lys 770 775 780 Leu Arg Phe Glu Ala Phe Lys Asn Leu Leu Arg Gln Asn Val Gly Phe 785 790 795 800 Tyr Asp Asp Ile Arg His Gly Thr Gly Lys Leu Cys Thr Arg Phe Ala 805 810 815 Thr Asp Ala Pro Asn Val Arg Tyr Val Phe Thr Arg Leu Pro Gly Val 820 825 830 Leu Ser Ser Val Val Thr Ile Ile Gly Ala Leu Val Ile Gly Phe Ile 835 840 845 Phe Gly Trp Gln Leu Ala Leu Ile Leu Met Val Met Val Pro Leu Ile 850 855 860 Ile Gly Ser Gly Tyr Phe Glu Met Arg Met Gln Phe Gly Lys Lys Met 865 870 875 880 Arg Asp Thr Glu Leu Leu Glu Glu Ala Gly Lys Val Ala Ser Gln Ala 885 890 895 Val Glu Asn Ile Arg Thr Val His Ala Leu Asn Arg Gln Glu Gln Phe 900 905 910 His Phe Met Tyr Cys Glu Tyr Leu Lys Glu Pro Tyr Arg Glu Asn Leu 915 920 925 Cys Gln Ala His Thr Tyr Gly Gly Val Phe Ala Phe Ser Gln Ser Leu 930 935 940 Leu Phe Phe Met Tyr Ala Val Ala Phe Trp Ile Gly Ala Ile Phe Val 945 950 955 960 Asp Asn His Ser Met Gln Pro Ile Asp Val Tyr Arg Val Phe Phe Ala 965 970 975 Phe Met Phe Cys Gly Gln Met Val Gly Asn Ile Ser Ser Phe Ile Pro 980 985 990 Asp Val Val Lys Ala Arg Leu Ala Ala Ser Leu Leu Phe Tyr Leu Ile 995 1000 1005 Glu His Pro Ser Glu Ile Asp Asn Leu Ser Glu Asp Gly Val Thr Lys 1010 1015 1020 Lys Ile Ser Gly His Ile Ser Phe Arg Asn Val Tyr Phe Asn Tyr Pro 1025 1030 1035 1040 Thr Arg Arg Gln Ile Arg Val Leu Arg Gly Leu Asn Leu Glu Ile Asn 1045 1050 1055 Pro Gly Thr Thr Val Ala Leu Val Gly Gln Ser Gly Cys Gly Lys Ser 1060 1065 1070 Thr Val Met Ala Leu Leu Glu Arg Phe Tyr Asn Gln Asn Lys Gly Val 1075 1080 1085 Ile Thr Val Asp Gly Glu Asn Ile Arg Asn Met Asn Ile Arg Asn Leu 1090 1095 1100 Arg Glu Gln Val Cys Ile Val Ser Gln Glu Pro Thr Leu Phe Asp Cys 1105 1110 1115 1120 Thr Ile Met Glu Asn Ile Cys Tyr Gly Leu Asp Asp Pro Lys Pro Ser 1125 1130 1135 Tyr Glu Gln Val Val Ala Ala Ala Lys Met Ala Asn Ile His Asn Phe 1140 1145 1150 Val Leu Gly Leu Pro Glu Gly Tyr Asp Thr Arg Val Gly Glu Lys Gly 1155 1160 1165 Thr Gln Leu Ser Gly Gly Gln Lys Gln Arg Ile Ala Ile Ala Arg Ala 1170 1175 1180 Leu Ile Arg Asp Pro Pro Ile Leu Leu Leu Asp Glu Ala Thr Ser Ala 1185 1190 1195 1200 Leu Asp Thr Glu Ser Glu Lys Ile Val Gln Asp Ala Leu Glu Val Ala 1205 1210 1215 Arg Gln Gly Arg Thr Cys Leu Val Ile Ala His Arg Leu Ser Thr Ile 1220 1225 1230 Gln Asp Ser Asp Val Ile Val Met Ile Gln Glu Gly Lys Ala Thr Asp 1235 1240 1245 Arg Gly Thr His Glu His Leu Leu Met Lys Asn Asp Leu Tyr Lys Arg 1250 1255 1260 Leu Cys Glu Thr Gln Arg Leu Val Glu Ser Gln 1265 1270 1275 3512 base pairs nucleic acid double linear cDNA 7 CCCGTTGTTG CCGGTGCTAT AGCGGAGGAG ACTTTCTCAT CGATACGAAC CGTACACTCG 60 TTATGTGGCC ATAAAAGAGA GCTAACAAGG CAGCGTTGGA GAAAGGACGT CAGACAGGCC 120 TTGTCAAATA TTTCTATATG GGTGTTGGTG TGAGATTTGG TCAGATGTGT ACCTATGTGT 180 CCTACGCCTT GGCTTTTTGG TATGGCAGTG TACTGATCAT CAACGACCCT GCATTGGATC 240 GTGGCCGAAT TTTCACAGTC TTTTTGCTGT GATGTCCGGC TCAGCAGCTC TCGGCACATG 300 TCTGCCACAT CTTAACACCA TATCCATCGC TCGAGGAGCG GTACGAAGTG TACTGTCAGT 360 GATTAATAGT CGTCCAAAAA TCGATCCCTA TTCGTTAGAT GGCATTGTGC TCAACAATAT 420 GAGAGGATCT ATTCGCTTCA AGAACGTGCA TTTCTCCTAT CCTTCCCGAA GAACATTGCA 480 GATATTGAAA GGTGTGTCAC TGCAAGTGTC GGCTGGCCAA AAAATTGCTT TGGTGGGTTC 540 AAGCGGTTGT GGAAAGTCAA CGATCGTCAA TTTATTATTG AGATTTTATG ATCCGACAAG 600 GGGAAAGGTA ACCATAGATG ATATTGATGT GTGTGATCTC AACGTGCAAA AACTTCGTGA 660 ACAAATCGGT GTTGTTAGTC AGGAACCAGT GCTTTTCGAT GGCACACTAT TCGAAAATAT 720 CAAGATGGGT TATGAACAGG CCACAATGGA GGAGGTCCAA GAAGCGTGCC GTGTGGCGAA 780 TGCTGCCGAC TTCATCAAAC GACTTCCAGA AGGTTACGGC ACCCGAGTTG GTGAACGTGG 840 TGTGCAGTTA AGTGGCGGAC AAAAGCAGCG AATTGCCATA GCTCGTGCGA TCATCAAGAA 900 CCCTCGCATA CTGCTGCTCG ATGAAGCCAC CAGTGCTCTA GACACAGAAG CGGAATCAAT 960 CGTGCAAGAG GCTCTGGAGA AGGCTCAAAA AGGGAGAACA ACCGTCATTG TAGCGCATCG 1020 TCTGTCTACT ATCAGAAACG TGGATCAGAT TTTCGTTTTC AAGAACGGAA CGATCGTTGA 1080 GCAGGGCACT CATGCCGAGT TGATGAACAA ACGTGGAGTA TTCTTTGAAA TGACTCAAGC 1140 ACAAGTCCTC CGACAAGAGA AGGAAGAGGA AGTTTTAGAA AATACGGAAC CAGTAGCGAA 1200 GTGTCAAGAG GTATCCCTCC CTGCTCCTGA TGTCACTATT TTGGCTCCCC ATGAGGAACA 1260 ACCCGAGCTA CCTAGCCCGC CGGGTCGGTT AGAAAATACA AAGCAACATG AGCATCTCTG 1320 AATGTCTTTG TCTGAGATAG CGATGCGGAA TCCGATGTCG TGTCACCGGA TATTGCATTA 1380 CCCCATCTTA GTTCACTTCG ATCCCGTAAA GAATCCACAA GAAGTGCTAT CTCCGCGGTC 1440 CCCAGCGTTC GAAGTATGCA AATCGAAATG GAGGACCTTC GTGCCAAACC AACTCCAATG 1500 TCGAAAATTT TCTATTTTAA CCGTGACAAA TGGGCATATT TCATTTTGGG ACTCATCGCC 1560 TGTATTATTA CTGGAACTGT TACACCGACA TTTGCAGTTT TATATGCGCA GATCATACAG 1620 GTATACTCGG AACCTGTTGA TCAAATGAAA GGCCATGTGC TGTTCTGGTG TGGAGCTTTC 1680 ATCGTCATTG GTCTCGTACA CGCTTTTGCG TTCTTTTTCT CGGCTATTTG TTTGGGACGT 1740 TGCGGCGAAG CGTTAACGAA AAAATTACGT TTCGAGGCGT TCAAGAACCT TCTGCGACAG 1800 GATGTGGGAT TCTACGACGA TATCCGACAC GGTACCGGTA AACTCTGTAC GCGATTTGCT 1860 ACAGATGCAC CCAATGTCCG ATATGTGTTC ACTCGACTTC CGGGTGTGCT TTCATCGGTG 1920 GTGACCATAA TTGGAGCTTT GGTTATTGGA TTCATCTTCG GGTGGCAGCT GGCTTTGATT 1980 CTTATGGTGA TGGTACCGTT GATCATCGGT AGTGGATACT TCGAGATGCG CATGCAGTTT 2040 GGTAAGGAGA TGCGTGACAC AGAGCTTCTT GAAGAGGCTG GGAAAGTTGC CTCTCAAGCC 2100 GTGGAGAACA TTCGTACCGT GCATGCCCTG AATAGGCAAG AGCAGTTCCA TTTCATGTAT 2160 TGCGAGTATT TGAAGGAACC CTATCGAGAA AATCTTTGCC AGGCGCACAC CTACGGGGGT 2220 GTATTCGCGT TCTCACAATC GTTGTTATTC TTTATGTATG CTGTAGCATT TTGGATTGGT 2280 GCAATCTTCG TGGACAACCA CAGCATGCAA CCGATTGACG TTTACCGAGT ATTTTTCGCG 2340 TTCATGTTTT GTGGACAAAT GGTCGGCAAC ATTTCTTCTT TTATTCCTGA CGTTGTGAAA 2400 GCTCGCCTGG CTGCATCGCT CCTTTTCTAC CTTATCGAAC ACCCATCAGA AATTGATAAT 2460 TTGTCCGAGG ATGGTGTCAC GAAGAAAATC TCTGGTCATA TCTCGTTCCG CAATGTCTAT 2520 TTCAATTATC CGACAAGAAG ACAGATCAGA GTACTCCGTG GACTTAACCT AGAGATAAAT 2580 CCTGGCACGA AGGTAGCGCT TGTTGGGCAG TCTGGTTGTG GAAAAAGCAC TGTGATGGCG 2640 TTGTTGGAAC GGTTTTACAA TCAAAACAAG GGCGTGATTA CGGTGGACGG CGAAAACATC 2700 AGAAACATGA ACATACGCAA TCTTCGTGAG CAAGTGTGTA TTGTAAGCCA GGAACCAACG 2760 CTGTTCGACT GTACCATCAT GGAAAACATC TGTTACGGTC TCGATGACCC CAAGCCGTCC 2820 TACGAACAGG TTGTTGCTGC AGCAAAAATG GCGAACATTC ACAATTTTGT GCTGGGACTA 2880 CCAGAGGGTT ACGATACGCG TGTTGGTGAG AAAGGCACTC AGCTGTCAGG CGGACAGAAG 2940 CAACGAATAG CCATAGCCAG AGCGCTGATT CGAGATCCGC CTATACTTCT GCTGGATGAG 3000 GCGACAAGCG CGCTGGATAC CGAGAGTGAA AAGATCGTGC AAGACGCCCT AGAGGTTGCT 3060 CGCCAAGGTA GAACGTGCCT TGTAATTGCC CATCGCCTTT CTACAATTCA AGACAGTGAC 3120 GTCATAGTGA TGATCCAGGA GGGGAAAGCT ACAGACAGAG GCACTCATGA ACATTTACTG 3180 ATGAAGAACG ATCTATACAA ACGGCTATGC GAAACACAAC GACTCGTTGA ATCACAATGA 3240 GTTTTTAGTG CCAATCGATA GTGATCGATA AGCTATGGAT TAGTCTTTAA CACTTACTGA 3300 TCACAAATTT TATCTCGTGC TTTATTCTAA TGTACATATG TAACGGTTTT GATCTTACAT 3360 ATCTTGTAAT TGGTCCTCAC TATCATAATG CCTTTAGTAG TACATTAACA GTTTTATTAA 3420 TACAACTTAA GTAACATATT AACAATTTTA TTAATATAAC TTAAGTAAGA TATTGACAGT 3480 TTTATTAATT TGGAGGATTT ATAATAAAAC TT 3512 2681 base pairs nucleic acid double linear cDNA 8 CCCGACTTCC GGAAGGTTAC GGCACCCGAG TAGGTGAACG TGGTGTACAA CTAAGTGGCG 60 GACAAAAGCA GCGCATCGCT ATTGCTCGCG CCATCATTAA AAACCCTCGT ATACTTCTGC 120 TTGACGAAGC CACCAGTGCT CTGGACACAG AGGCGGAATC AATTGTGCAA GAAGCTCTCG 180 AGAAAGCTCA AAAAGGACGA ACGACCGTCA TTGTAGCGCA TCGCCTATCT ACCATCAGAA 240 ATGTCGATCA AATTTTCGTC TTCAAGAATG AAACGATTGT TGAGCAGGGT ACACATGCAG 300 AGTTGATGAA CAAACGAGGA GTGTTCTTTG AAATGACTCA AGCACAGGTC CTTCGACAAG 360 AAAAGGAAGA GGAGGTCTTA GAAAATACGG AACCAGTAGC GAAGTGTCAA GAGGCATCCT 420 TTCCTGCTCC TGATGTCACT ATTTTGACTC CCCATGACGA ACAACCCGAG CTACTTAGCC 480 CGCCGGATAG CGATGCGGAA TCCGACGTCA TGTCACCGGA TCTTGGCTTA CCCCATCTTA 540 GTTCACTTCG ATCACGTAAA GAGTCCACAA GAAGTGCTAT TTCCGCAGTC CCCAGCGTTC 600 GGAGTATGCA GATCGAAATG GAGGACCTTC GTGCCAAACC GACTCCGATG TCGAAAATTT 660 TCTATTTCAA CCGTGACAAA TGGGGATTTT TCATTTTGGG ACTCATCGCC TGTATTATAA 720 CTGGAACTGT TACACCGACA TTTGCAGTTT TATATGCGCA GATCATACAG GTATACTCGG 780 AACCTGTTGA TCAAATGAAA GGCCATGTGC TGTTTTGGTG TGGAGCTTTC ATCGTCATTG 840 GTCTCGTACA CGCATTTGCG TTCTTTTTCT CGGCCATTTG TCTGGGACGT TGCGGCGAAG 900 CTTTAACGAA GAAGTTACGT TTCGAGGCGT TCAAGAACCT TCTCCGACAA GATGTGGGAT 960 TCTACGACGA TATCCGACAC GGTACCGGTA AACTCTGTAC GCGATTTGCT ACAGATGCAC 1020 CCAATGTTCG ATATGTGTTC ACTCGACTTC CGGGTGTACT TTCATCGGTG GTGACCATAA 1080 TCGGAGCTTT GGTTATTGGA TTTATTTTCG GGTGGCAGCT GGCCTTGATT CTTATGGTCA 1140 TGGTACCGTT GATCATTGGC AGTGGATACT TCGAGATGCG CATGCAGTTT GGTAAAAAGA 1200 TGCGTGACAC AGAGCTTCTT GAAGAGGCTG GGAAAGTTGC CTCACAAGCC GTAGAGAATA 1260 TTCGTACCGT ACATGCCCTG AATCGGCAAG AGCAGTTCCA TTTCATGTAC TGCGAGTATT 1320 TGAAGGAACC CTATCGAGAG AATCTTTGCC AGGCGCACAC TTACGGGGGT GTATTCGCGT 1380 TTTCACAGTC GTTGTTATTC TTTATGTATG CTGTAGCATT TTGGATTGGT GCAATCTTCG 1440 TGGACAACCA CAGCATGCAA CCGATTGATG TTTACCGAGT ATTTTTCGCG TTCATGTTTT 1500 GTGGACAAAT GGTTGGCAAC ATTTCGTCCT TCATCCCTGA TGTTGTGAAA GCTCGCCTGG 1560 CTGCATCGCT CCTTTTCTAC CTCATCGAAC ACCCATCAGA AATTGATAAC TTGTCCGAGG 1620 ATGGTGTCAA GAAGAAAATC TCTGGTCACA TCTCGTTCCG CAATGTCTAT TTCAATTACC 1680 CGACGAGAAG GCAGATCAGA GTACTCCGTG GACTTAACCT AGAGATAAAT CCTGGCACGA 1740 CGGTAGCGCT TGTTGGACAA TCTGGTTGTG GAAAAAGCAC TGTGATGGCG TTGTTGGAAC 1800 GCTTTTACAA TCAAAACAAG GGCGTGATTA CGGTTGACGG CGAAAACATC AGAAACATGA 1860 ACATACGCAA TCTCCGTGAG CAAGTATGTA TAGTCAGCCA GGAACCAACA CTGTTCGACT 1920 GTACCATCAT GGAAAACATC TGTTACGGAC TCGATGACCC CAAACCGTCC TACGAACAGG 1980 TTGTTGCGGC AGCAAAAATG GCGAACATCC ACAATTTTGT GCTGGGACTG CCAGAGGGTT 2040 ATGACACGCG TGTTGGCGAG AAAGGCACTC AGCTGTCAGG CGGACAAAAG CAAAGAATAG 2100 CCATAGCCCG AGCGCTGATC CGAGATCCGC CTATACTTCT GCTGGATGAG GCGACAAGCG 2160 CTCTGGACAC GGAGAGTGAG AAGATCGTGC AAGACGCCCT AGAGGTTGCT CGCCAAGGTA 2220 GAACGTGCCT TGTAATTGCC CACCGCCTTT CTACAATTCA AGACAGTGAC GTCATAGTGA 2280 TGATCCAGGA GGGAAAAGCT ACAGACAGAG GCACTCATGA ACATTTACTG ATGAAGAACG 2340 ATCTATACAA ACGGCTATGC GAAACACAAC GACTCGTTGA ATCACAATGA GTTTTTAGTG 2400 CCGATCGATA GTGATCGATA AGCTATGGAT TAGTCTTCAA CACTTACTGA TCATATGACT 2460 ATCTCGTGCT TTATTATAAT GTACATATGT AATGGTTTTG ATGTAAGTTA AGTTATAATT 2520 GGTCTTCACT ATCATAATGC CTTTAGTAAT GCATTAACAC TTTTATAATA TAACTTGAAT 2580 AACATATTGA CAGTTTTATT AATATAACTT AAATAAGATA TTGACAGTTT TATTAATTTG 2640 GAGAATTTAT AATGAAACTT CTGGATTCCT GCAGCCCGGG G 2681 19 base pairs nucleic acid single linear cDNA 9 GAAATGACTC AAGCACAAG 19 18 base pairs nucleic acid single linear cDNA 10 AGACAAAGAC ATTCAGAG 18 17 base pairs nucleic acid single linear cDNA 11 ACNGTNGCNY TNGTNGG 17 17 base pairs nucleic acid single linear cDNA 12 GCNSWNGTNG CYTCRTC 17 

We claim:
 1. A purified and isolated nucleic acid molecule, extracted from a nematode, encoding a P-glycoprotein which regulates resistance to a macrocyclic lactone compound, wherein the nucleic acid molecule has a nucleotide sequence which exhibits an allelic pattern consistent with the nucleotide sequence encoding PGP-A set forth in SEQ ID NO:3, PGP-A-3′ set forth in SEQ ID NO:5 (ATCC accession number 98336), PGP-B, PGP-B-3′ set forth in SEQ ID NO:8 (ATCC accession number 98307), PGP-O or PGP-O-3′ set forth in SEQ ID NO:7 (ATCC accession number 98309); the complementary strands thereof or a nucleotide sequence which hybridizes at about 65 degrees in the presence of a dextran buffer over at least about 4 hours to the nucleotide sequence encoding PGP-A, PGP-A-3′, PGP-B, PBP-B-3′, PGP-O or PGP-O-3′.
 2. The nucleic acid molecule or the fragment according to claim 1, wherein the nucleic acid molecule is extracted from Haemonchus contortus.
 3. The nucleic acid molecule or a fragment according to claim 2, wherein the nucleic acid molecule or the fragment has a nucleotide sequence encoding PGP-A set forth in SEQ ID NO:3, PGP-A-3′ set forth in SEQ ID NO:5 (ATCC accession number 5 98336), PGP-B, PGP-B-3′ set forth in SEQ ID NO:8 (ATCC accession number 98307), PGP-O or PGP-O3′ set forth in SEQ ID NO:7 (ATCC accession number 98309); the complementary strands thereof or a nucleotide sequence which hybridizes at about 65° C. in the presence of a dextran buffer over at least about 4 hours to the nucleotide sequence encoding PGP-A, PGP-A-3′, PGP-B, PGP-B-3′, PGP-O or PGP-O-3′.
 4. A biologically functional plasmid or viral vector containing the nucleic acid molecule according to claim
 1. 5. A suitable host cell stably transformed or transfected by a vector comprising the nucleic acid molecule according to claim
 1. 6. A process f or the production of a polypeptide product having part or all of the primary structural conformation and the biological activity of a P-glycoprotein homolog product, said process comprising: growing, under suitable nutrient conditions, procaryotic or eucaryotic host cells transformed or transfected with a nucleic acid molecule, according to claim 1, in a manner allowing expression of said polypeptide product, and isolating the desired polypeptide product of the expression of said nucleic acid molecule or said fragment.
 7. A P-glycoprotein homolog product of the expression in a procaryotic or eucaryotic host cell of the nucleic acid molecule according to claim
 6. 8. A recombinant nucleic acid molecule encoding a P-glycoprotein homolog which regulates resistance to a macrocyclic lactone compound.
 9. The recombinant nucleic acid molecule or the fragment according to claim 8, wherein the nucleic acid molecule has a nucleotide sequence encoding PGP-A set forth in SEQ ID NO:3, PGP-A-3′ set forth in SEQ ID NO:5 (ATCC accession number 98336), PGP-B, PGP-B-3′ set forth in SEQ ID NO:8 (ATCC accession number 98307), PGP-O or PGP-O-3′ set forth in SEQ ID NO:7 (ATCC accession number 98309); the complementary strands thereof or a nucleotide sequence which hybridizes at about 65° C. in the presence of a dextran buffer over at least about 4 hours to the nucleotide sequence encoding PGP-A, PGP-A-3′, PGP-B, PGP-B-3′, PGP-O or PGP-O-3′. 